Injection mold design system and injection mold design method

ABSTRACT

An injection mold design method for correcting a profile of a product to be fabricated into a releasable profile from a mold to design an injection mold based on a corrected product shape, utilizing a storage device for storing information of the product shape and mold profile, a display device for displaying the product shape or the mold profile on a screen based on the information read from the storage device, an input device for inputting designation information necessary for correction of the product shape or the mold profile, and a controlling device for unloading information of lines or planes being obstructive to correction of the product shape and the mold profile in the storage device in response to the designation information input by the input device. The method comprises removing lines or planes from the screen, and replotting the lines or the planes on the screen in terms of the information of lines or planes unloaded into the storage device after the correction operation of the product shape or the mold profile is completed.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an injection mold design systemand an injection mold design method and, more particularly, a designsupport system for a mold used for fabricating resin (plastics)injecting moldings and a design method for designing the mold.

[0003] 2. Description of the Related Art

[0004] In recent years, according to demands for more variety of productdesign, users' various usages etc., plastics have been widely used asmaterial of enclosures for electrical products since they may present anattractive appearance and may be molded arbitrarily. In addition, itentails such advantages that reduction in the number of parts andsimplification of assembly may be attained. This is because seats,bosses (projections), etc., these being used for mounting printedcircuit boards and other parts, and reinforcing members such as ribs maybe formed integrally with the enclosures if the enclosures arefabricated by resin injection molding.

[0005]FIG. 1A shows an example of moldings (molded products) formed byresin injection molding. In FIG. 1A, a reference 1 denotes a moldingused as an enclosure of a portable electronic device, and a reference 2denotes a bore portion provided in the molding 1. After preparing themold in which a cavity having the same profile as that of the product isin advance formed, melted resin is filled into the cavity and thencured, so that the molding 1 with a shape shown in FIG. 1A may beformed. At this time, the bore portion 2 may be formed by nests arrangedin the mold.

[0006]FIG. 1B shows a configuration of the mold. In FIG. 1B, a reference3 denotes a cavity (female mold) for defining an outer shape of themolding 1, and a reference 4 denotes a core (male mold) for defining aninner shape of the molding 1. When the cavity 3 is put on the core 4,the cavity corresponding to the products profile to be formed may beformed between them.

[0007]FIG. 1C shows a configuration of an injection molding machine onwhich the mold is mounted. With being arranged so as to oppose to eachother in the vertical direction, the cavity 3 and the core 4 are clampedon a cavity plate 3A and a core plate 4A respectively. The cavity plate3A may be driven by a driving apparatus (not shown) to move in thevertical direction. A reference 5 denotes a runner stripper plate inwhich a runner (not shown) is formed to introduce the resin 7 into thespace in the mold. The runner stripper plate 5 may be placed on thecavity plate 3A. When the molds are opened, the runner stripper plate 5may then be separated from the cavity plate 3A to enable the resin curedin the runner to be removed from the runner. A reference 6 denotes agate (pouring gate) formed in the mold. Resin 7 is filled into thecavity in the mold via the gate 6.

[0008] A reference 8 denotes a gas vent (breathing hole) which isprovided in the mold to exhaust the air from the space in the mold tothe exterior when the resin is poured into the space in the mold. Areference 9 denotes a cooling water path provided in the mold. Since theresin to be filled into the mold is heated at a temperature of a fewhundreds ° C., a temperature of the mold is raised when the resin isfilled into the mold. As a result, drawbacks such as not only reductionin molding efficiency but also warpage, twist, etc. of the product arecaused. In order to prevent the drawbacks, the mold is cooled by flowingwater through the cooling water path 9. Usually, the cooling water path9 is provided on the core 4 side.

[0009] A reference 10 denotes an extruder portion for extruding themoldings 1 from the core 4. The extruder portion 10 has a rod-likemember referred to as an ejector pin. The moldings 1 can be extrudedfrom the core 4 by inserting the ejector pin into a through holeprovided in the core 4.

[0010] In any event, since the injection mold is composed of the cavity3 and the core 4, as mentioned above, the mold must be split into thecavity 3 side and the core 4 side when designing the mold. The splitplane is called a parting plane. In case there is caused an undercutportion in the products to be fabricated, the moldings cannot bestripped off from the mold if the parting plane is set incorrectly. Herethe undercut portion may be defined as a portion serving as anengagement formed in the mold opening direction when the product istaken out from the molds. If the undercut portion exists, considerationfor providing a slide structure to the mold or the like should be takeninevitably.

[0011] In order to strip the product off from the mold readily, slightslopes (draft slopes) are provided on the surface of the mold so as toprevent inner surfaces of the mold from being formed perpendicularly tothe parting plane. In the prior art, in the case of the mold having arelatively simple profile, mold designers be able to design the moldaccording to drawings prepared for the product while considering partingplane, draft slope, etc. Conversely, as for the product which must bedesigned by means of a plenty of free-form surfaces to achieve the highdesign property, it would become difficult to illustrate the profile ofthe product in the drawings. As a countermeasure to this drawback, firstthe product model (model) is formed, then profile lines of the productmodel are illustrated with many dots, and then the profile of theproduct is converted into numeric data by correlating these dots witheach other in terms of digitizing process. Then NC (Numeric Control)data used for cutting process and electric discharge machiningelectrodes are then prepared for based on the numeric data. According tothese data, the mold may be then fabricated by the electric dischargemachining electrodes.

[0012] In the meanwhile, there are some cases where the mold may bedesigned by means of the three dimensional CAD (Computer-Aided Design)system. In such cases, data of the product shape are first input intothe CAD system, then the product shape or the mold block (i.e., virtualblock displayed on the screen for illustrating an outer shape of themold) in which a cavity corresponding to the product shape is formed isdepicted on the display. While monitoring the screen of the display, thedesigner may draw the parting line on the screen to form the partingplane or select the planes to which a draft slope is provided. The CADsystem may thus output numeric data to form the mold in compliance withthese setting conditions.

[0013] However, in the method where the designer has to design the moldon the basis of the design drawings, the designer must design the moldwhile considering undercut, draft slope, etc. as mentioned above.Therefore, it can be seen that, in the case of the product withcomplicate profile, it would become difficult for the designer todetermine a solid product shape from the drawings. For this reason,according to this method, problems have been arisen that man-hour indesign is increased and design error is prone to generate.Alternatively, in the method where data used for fabricating the moldare generated from the product model, there are some problems that,since the product model must be formed to have a precise profile, thedesigner must be well practiced in forming the product model and muchtime must also be consumed to form the product model.

[0014] Moreover, in the method where the three dimensional CAD system isused, the troublesome procedures would be required and further a greatdeal of skill would be required for the designer since the mold designermust design parting plane, draft slopes, etc. on the basis of imagedisplayed on the screen of the display. Because of the causes such asmissing of the undercut portion, the mold designer is apt to generateerrors in design.

SUMMARY OF THE INVENTION

[0015] It is an object of the present invention to provide a designsystem capable of designing an injection mold readily and in short timeand a design method employed in the same.

[0016] According to the injection mold design system of the presentinvention, in case the product shape or the mold profile should becorrected, since lines or planes being obstructive to profile correctioncan be unloaded to a storing means temporarily, the designer may correctthe product shape or the mold profile while monitoring the displayscreen on which only lines or planes indispensable to the certainprofile correction are depicted. Therefore, with displaying astereoscopic drawing and a projection drawing of the product on thedisplay device, the designer may execute correction of shrinkage rate,extraction of parting line, provision of draft slope, etc. in aninteractive manner.

[0017] According to the injection mold design method of the presentinvention, design items can be reduced by preparing parameters of themold parts and fixing parts as patternized information, and in additioncorrection, change, etc. of the product shape and the mold profile canbe effected automatically. Consequently, man-hour of design in typicaldesign operations can be significantly reduced.

[0018] According to the injection mold design method of the presentinvention, features of the mold which being indispensable to formationof the mold can be grasped by extracting candidates of split borderlinesof the mold. In addition, lack of knowledge and experience as to themold design can be made up for by utilizing a loop check function forthe split borderlines and a nest split function. Thus, the design methodof the present invention enables the designer having little experienceto execute the mold design.

[0019] With the above, the present invention may extremely contribute tothe mold design support system capable of executing correction of theproduct shape, design of the mold, and design of manufacturing jigs inan interactive manner.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1A is a perspective view illustrating an example of amoldings according to the conventional injection mold design method;

[0021]FIG. 1B is a side view showing molds used for forming the exampleof the moldings in FIG. 1A;

[0022]FIG. 1C is a side view showing an injection molding machine onwhich the molds shown in FIG. 1B are mounted;

[0023]FIG. 2 is a view showing a configuration of an injection molddesign system according to embodiments of the present invention;

[0024]FIGS. 3A to 3G are views illustrating various display functions ofa display device according to embodiments of the present invention;

[0025]FIGS. 4A to 4C are flowcharts, when taken together, illustratinginjection mold design according to embodiments of the present invention;

[0026]FIG. 5 is a perspective view showing a cavity and a core in acoupled state according to embodiments of the present invention;

[0027]FIG. 6 is a perspective view showing the cavity and the core in aseparated state according to embodiments of the present invention;

[0028]FIGS. 7A to 7C are enlarged partial sectional views showing themolds when designing a parting plane according to embodiments of thepresent invention;

[0029]FIGS. 8A and 8B are perspective views respectively showing splitof a nest portion according to embodiments of the present invention;

[0030]FIG. 9A is a perspective view showing split of the nest portionaccording to embodiments of the present invention;

[0031]FIG. 9B is a side view showing the nest portion in FIG. 9A;

[0032]FIG. 9C is a plan view showing the nest portion in FIG. 9A;

[0033]FIG. 10 is a flowchart illustrating profile detection of anoutermost periphery and through holes of a product shape according to afirst embodiment of the present invention;

[0034]FIG. 11 is a perspective view showing the product shape whendetecting the outermost periphery according to the first embodiment ofthe present invention;

[0035]FIG. 12 is a flowchart illustrating draft-sloped plane detectionaccording to a second embodiment of the present invention;

[0036]FIG. 13 is a flowchart illustrating assignment of priority levelto the draft-sloped plane according to a third embodiment of the presentinvention;

[0037]FIG. 14 is a perspective view showing the product shape before andafter magnification when assigning the priority level according to thethird embodiment of the present invention;

[0038]FIGS. 15A to 15C are views respectively explaining shrinkage ofthe product shape when assigning the priority level according to thethird embodiment of the present invention;

[0039]FIG. 16 is a flowchart illustrating provision of draft slopeaccording to a fourth embodiment of the present invention;

[0040]FIG. 17 is a perspective view showing circular cone when providingthe draft slope according to the fourth embodiment of the presentinvention;

[0041]FIG. 18 is an enlarged perspective view showing projection of aparting line when providing the draft slope according to the fourthembodiment of the present invention;

[0042]FIG. 19 is a perspective view showing the product shape havingdraft-sloped plane according to the fourth embodiment of the presentinvention;

[0043]FIG. 20 is a flowchart illustrating formation of the parting lineaccording to a fifth embodiment of the present invention;

[0044]FIGS. 21A and 21B are perspective views showing a circularcylinder when forming the parting line according to a fifth embodimentof the present invention;

[0045]FIG. 22 is a plan view showing the product shape when forming theparting line according to the fifth embodiment of the present invention;

[0046]FIG. 23 is a flowchart illustrating loop check of the parting lineaccording to a sixth embodiment of the present invention;

[0047]FIG. 24 is a perspective view showing line elements when checkingthe parting line according to the sixth embodiment of the presentinvention;

[0048]FIG. 25 is a flowchart illustrating detection of undercutaccording to a seventh embodiment of the present invention;

[0049]FIG. 26 is a perspective view showing an opening portion whendetecting the undercut according to the seventh embodiment of thepresent invention;

[0050]FIG. 27 is a perspective view showing detection of openingportions other than the undercut according to the seventh embodiment ofthe present invention;

[0051]FIGS. 28A and 28B are flowcharts, when taken together,illustrating check process of releasability of the product shapeaccording to an eighth embodiment of the present invention;

[0052]FIGS. 29A to 29C are flowcharts, when taken together, illustratingformation process of the parting plane according to a ninth embodimentof the present invention;

[0053]FIGS. 30A to 30C are perspective views respectively showing splitof the mold into the cavity and the core according to the ninthembodiment of the present invention;

[0054]FIGS. 31A to 31C are flowcharts, when taken together, illustratingdetection process of a depth of the core and split candidate location ofthe core according to a tenth embodiment of the present invention;

[0055]FIG. 32 is a side view showing the cavity and the core whendesigning split nest of the mold according to the tenth embodiment ofthe present invention;

[0056]FIG. 33 is a flowchart illustrating assignment of priority levelto split line candidates of the core according to an eleventh embodimentof the present invention;

[0057]FIG. 34 is a side view showing the cavity and the core whenassigning the priority level according to the eleventh embodiment of thepresent invention;

[0058]FIGS. 35A and 35B are flowcharts, when taken together,illustrating arrangement of mold base according to a twelfth embodimentof the present invention;

[0059]FIG. 36 is a fragmental sectional view showing a fixing structureof the mold parts according to the twelfth embodiment of the presentinvention;

[0060]FIGS. 37A and 37B are perspective view showing a fixing structureof the mold parts according to the twelfth embodiment of the presentinvention;

[0061]FIG. 38 is a view showing an image on the display device whendesigning a gate structure according to a thirteenth embodiment of thepresent invention;

[0062]FIG. 39 is a flowchart illustrating gate design according to thethirteenth embodiment of the present invention;

[0063]FIG. 40 is a perspective view showing the gate structure accordingto the thirteenth embodiment of the present invention;

[0064]FIG. 41A is a perspective view showing the gate structureaccording to the thirteenth embodiment of the present invention;

[0065]FIGS. 41B to 41D are sectional views showing an ejector pinaccording to a sixteenth embodiment of the present invention;

[0066]FIG. 42 is a view showing an image on the display device whendesigning the gate structure according to a thirteenth embodiment of thepresent invention;

[0067]FIG. 43 is a view showing an image on the display device whendesigning a runner structure according to a fourteenth embodiment of thepresent invention;

[0068]FIG. 44 is a flowchart illustrating runner design according to thefourteenth embodiment of th6 present invention;

[0069]FIG. 45 is a perspective view showing the runner structureaccording to the fourteenth embodiment of the present invention;

[0070]FIGS. 46A to 46D are sectional views showing the runner structureaccording to the fourteenth embodiment of the present invention;

[0071]FIG. 47 is a flowchart illustrating gas vent design according to afifteenth embodiment of the present invention;

[0072]FIG. 48 is a plan view showing the core when designing the gasvent structure according to the fifteenth embodiment of the presentinvention;

[0073]FIGS. 49A to 49C are views showing images on the display deviceobtained by superposing a plan view of the core and resinsuperplasticized analysis chart when designing the gas vent structureaccording to the fifteenth embodiment of the present invention;

[0074]FIG. 50 is a view showing an image on the display device whendesigning the ejector pin according to a sixteenth embodiment of thepresent invention;

[0075]FIG. 51 is a view showing another image on the display device whendesigning the ejector pin according to a sixteenth embodiment of thepresent invention;

[0076]FIG. 52 is a flowchart illustrating ejector pin design accordingto the sixteenth embodiment of the present invention;

[0077]FIG. 53 is a perspective view showing the ejector pin inconnection with the product shape according to the sixteenth embodimentof the present invention;

[0078]FIG. 54 is a view showing an image on the display device whendesigning a cooling path according to a seventeenth embodiment of thepresent invention;

[0079]FIG. 55 is an isometric drawing showing the mold when designingthe cooling path according to the seventeenth embodiment of the presentinvention;

[0080]FIGS. 56A and 56B are segmental side views showing the mold whendesigning a link structure according to an eighteenth embodiment of thepresent invention;

[0081]FIG. 57 is a view explaining dimensional tolerance according to anineteenth embodiment of the present invention;

[0082]FIG. 58 is a view illustrating a menu system of the mold designsystem according to a twentieth embodiment of the present invention;

[0083]FIGS. 59A and 59B are views respectively illustrating another menusystem of the mold design system according to the twentieth embodimentof the present invention;

[0084]FIG. 60 is a view illustrating use segments of mold design itemsaccording to the twentieth embodiment of the present invention;

[0085]FIG. 61 is a flowchart illustrating detection of the undercut inthe product shape according to the twenty-first embodiment of thepresent invention;

[0086]FIGS. 62A to 62C are views showing the product shape with theundercut according to the twenty-first embodiment of the presentinvention;

[0087]FIGS. 63A and 63B are views showing the product shape without theundercut according to the twenty-first embodiment of the presentinvention;

[0088]FIG. 64 is a flowchart illustrating extraction process of theparting line according to a twenty-second embodiment of the presentinvention;

[0089]FIG. 65A is a perspective view showing the product shape accordingto the twenty-second embodiment of the present invention;

[0090]FIG. 65B is a view showing the product shape viewed from the moldopening direction according to the twenty-second embodiment of thepresent invention;

[0091]FIGS. 66A to 66D are views illustrating displayed examples on thedisplay device when extracting the parting line according to thetwenty-second embodiment of the present invention;

[0092]FIGS. 67A and 67B are flowcharts, when taken together,illustrating formation process of the parting plane according to atwenty-third embodiment of the present invention;

[0093]FIGS. 68A to 68E are views showing the parting line and planeelements when forming the parting plane according to the twenty-thirdembodiment of the present invention;

[0094]FIG. 69 is a flowchart illustrating design process of the ejectorpin according to a twenty-fourth embodiment of the present invention;

[0095]FIGS. 70A to 70D are views showing screen images on the displaydevice when designing the ejector pin according to the twenty-fourthembodiment of the present invention;

[0096]FIG. 71 is a flowchart illustrating design process of the moldbase according to a twenty-fifth embodiment of the present invention;

[0097]FIG. 72 is a view illustrating screen images on the display devicewhen designing the mold base according to the twenty-fifth embodiment ofthe present invention;

[0098]FIG. 73 is a view showing a menu screen for the injection moldingmachine when designing the mold base according to the twenty-fifthembodiment of the present invention;

[0099]FIG. 74 is a flowchart illustrating usage of configuration fileaccording to a twenty-sixth embodiment of the present invention;

[0100]FIG. 75 is a view illustrating the contents of the configurationfile according to the twenty-sixth embodiment of the present invention;

[0101]FIG. 76 is a flowchart illustrating mold design, with attributesbeing considered in the mold design system, according to atwenty-seventh embodiment of the present invention;

[0102]FIG. 77 is a perspective view showing an injection mold devicewhen individual attributes are allotted to names of respective parts ofthe device, according to the twenty-seventh embodiment of the presentinvention;

[0103]FIG. 78 is a flowchart illustrating design process of holes of themold parts according to a twenty-eighth embodiment of the presentinvention;

[0104]FIGS. 79A to 79C are perspective views showing interferencebetween the cooling water path and the ejector pin holes according tothe twenty-eighth embodiment of the present invention;

[0105]FIG. 80 is a flowchart illustrating design process ofmanufacturing jigs of the mold parts according to a twenty-ninthembodiment of the present invention; and

[0106]FIGS. 81A to 81F are views illustrating screen images on thedisplay device when designing the manufacturing jigs according to thetwenty-ninth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0107] There will now be explained in detail preferred embodiments ofthe present invention with reference to accompanying drawingshereinafter.

[0108] An injection mold design system for correcting a profile of aproduct to be fabricated into a releasable profile from a mold to designan injection mold based on a corrected product shape, comprising storingmeans for storing information of product shape and mold profile,displaying means for displaying the product shape or the mold profile ona screen based on the information read from the storing means, inputtingmeans for inputting designation information necessary for correction ofthe product shape or the mold profile, and controlling means forunloading information of lines or planes being obstructive to correctionof the product shape and the mold profile into the storing means inresponse to the designation information input by the inputting means,removing the lines or the planes from the screen, and replotting theline or the planes on the screen in terms of the information of lines orplanes unloaded into the storing means after the correction operation ofthe product shape or the mold profile is completed.

[0109] In the injection mold design system, the lines or the planesbeing obstructive to the correction operation are removed from thescreen by the controlling means when the product shape is corrected intoa releasable profile. With this process, upon correcting the profile,missing of undercut portions and generation of the line or plane such asfillet being obstructive to correction operation can be prevented, sothat operability may be improved and design error may be prevented. Inthis event, according to the design system of the present invention,since information of the lines or planes removed from the screen arestored in the storing means, the lines or the planes may be replotted onthe screen after correction operation of the profile is completed.

[0110] In the design system of the present invention, the storing meansmay be provided wherein first design items used for correcting theproduct shape into the releasable profile from the mold, second designitems used for designing the mold, and third design items used forforming manufacturing jigs of the mold are stored.

[0111] Since the design items being roughly classified into three groupsare stored in the storing means, the product designer or the molddesigner may correct the product shape in compliance with the firstdesign items so as to enable the product to be readily released from themold. The mold designer may design the mold in compliance with thesecond design items. In addition, both the mold designer and the moldmanufucturer may design the manufacturing jigs in compliance with thethird design items. Consequently, since software resources stored in thestoring means may be commonly used by the product designer, the molddesigner, and the mold manufacturer, design operation of the mold may beconducted easily and quickly.

[0112] In the design system of the present invention, means is providedwhich may form dot lines on a constituting plane of the product beingperpendicular to the mold opening direction, and then detect whether ornot the dot lines can be projected onto other constituting plane in themold opening direction.

[0113] In case it has been detected that the dot lines formed on theconstituting plane of the product can be projected onto otherconstituting plane in the mold opening direction, the constituting planewould become obstructive in the mold opening direction. Therefore, theconstituting plane may be detected as the undercut portion.

[0114] In the design system of the present invention, means forconnecting an outermost peripheral profile of the product viewed fromthe mold opening direction and line segments of the product designatedby the designer so as to extract a split line of the product occupying acertain space may be provided.

[0115] If the outermost peripheral profile of the product viewed fromthe mold opening direction and the line segments of the productdesignated by the designer are connected, the designer may extract thesplit line of the product occupying a certain space in a mannerinteracting with the design system.

[0116] In the design system of the present invention, means is providedwhich may detect a flat plane constituted with the split line occupyinga certain space, then connect the detected flat plane and one of acircular cylinder surface, a circular cone surface, and a free-formsurface all being designated by the designer, and then form the splitplane to split the product into the cavity and the core.

[0117] By connecting the detected flat plane constituted with the splitline and one of the circular cylinder surface, the circular conesurface, and the free-form surface all being designated by the designer,the designer may form the split plane for splitting the product shapeinto the cavity and the core in a manner interacting with the designsystem.

[0118] In the design system of the present invention, means is providedwhich, when the designer has instructed a concerned location against theprofile of the core viewed in the mold opening direction, may detect thedesignated location and a height of the ejector pin for ejecting theproduct from the core and then form a hole profile with dimensions inputby the designer on the designated location.

[0119] By detecting the designated location against the core profileviewed in the mold opening direction and the height of the ejector pin,the designer may easily design the hole profile, for example, used forthe ejector pin for ejecting the product from the core, in a mannerinteracting with the design system.

[0120] In the design system of the present invention, means fordisplaying on one screen a profile of a mold base constituting the moldand an instruction window having boxes for inputting respectivedimensions of individual constituting parts of the mold base therein,and means for forming data of the mold base in compliance with the inputdimensions when the designer has input respective dimensions in theboxes of the instruction windows of the displaying means may beprovided.

[0121] According to the design system of the present invention, when thedesigner inputs respective dimensions of individual constituting partsof the mold in the instruction windows of the displaying means, data ofthe mold base may be formed in compliance with the input dimensions.Thus, while monitoring the profile of the mold base, the designer maydesign the mold base easily in a manner interacting with the designsystem.

[0122] In the design system of the present invention, storing means isprovided which may store at least information concerning display colorof characters, lines, symbols and regions, information concerning outputmethod of design information of the mold, and information concerningreference values required for each design of the mold. For purposes ofexample, the storing means may be composed of an erasable and writableread-only memory.

[0123] According to the design system of the present invention, thestoring means in which information relating to display color, outputmethod of design information, and reference values are stored may becomposed of the erasable and writable read-only memory. Therefore,although a plenty of automatic process have been employed, displaycolors of characters, lines, symbols and regions, output method ofinformation required for designing the mold, reference values requiredfor each design of the mold, and display method of respective parts datamay be modified arbitrarily. As a result, the mold design system beingmostly suitable for each designer can be built up.

[0124] In the design system of the present invention, designing means isprovided which may design the mold by using data in the group withselected name when the designer selects the group name of data necessaryfor design of the mold in compliance with the design items of the moldafter the designer allots respective names to groups of data relating tothe design items of the mold.

[0125] According to the design system of the present invention, when thedesigner selects a group name of data necessary for design of the mold,the design system may design automatically the mold in accordance withdata included in the group with selected name. Therefore, since thedesigner be able to reduce design items to be input into the designsystem, design operations may be simplified.

[0126] In the design system of the present invention, means is providedwhich may detect a separating distance between a particular hole andother hole of the mold parts, and then compares the separating distancebetween the particular hole and other hole with a preliminary setseparating reference value.

[0127] When the separating distance between the particular hole andother hole of the mold parts are compared with the preliminary setseparating reference value, and if the separating distance between theholes is less than the separating reference value, an abnormal approachbetween the holes may be detected in the course of design operation. Asa result, design error such as overlapping between the holes may beprevented.

[0128] In the design system of the present invention, means is providedwhich, when the designer designates a range of the manufacturing jigs tobe used for manufacturing the mold parts against the displayed moldparts, may form an ejected profile having a range of the manufacturingjigs of the mold parts as a sectional shape and transfer a profile ofthe mold parts to the ejected profile.

[0129] According to the design system of the present invention,

[0130] when the designer designates the range of the manufacturing jigson the displayed mold parts, the ejected profile having the range of themanufacturing jigs as the sectional shape may be formed, and the profileof the mold parts may be transferred onto the ejected profile. As aresult, the designer be able to design the manufacturing jigs of themold parts in a manner interacting with the design system.

[0131] As for the first design method according to the presentinvention, in the injection mold design method for designing the coreand the cavity by correcting the profile of the product to be fabricatedinto a releasable profile from the mold, then arranging the correctedproduct shape in the mold block being displayed on the screen to providea cavity corresponding to the product shape in the mold block, and thensplitting the mold block, part of lines or planes constituting theproduct shape or the mold profile may be removed temporarily from thescreen, and the lines or planes may be replotted on the screen after thecorrection operation of the product shape or the mold profile beingdisplayed on the screen is completed.

[0132] According to the injection mold design method of the presentinvention, part of the lines or planes constituting the product shape orthe mold profile may be removed temporarily from the screen, and thelines or planes may be replotted on the screen after completion ofprofile correction when the product shape or the mold profile beingdisplayed on the screen is corrected. Therefore, the designer may removelines or planes being obstructive to required operation from the screenon the display to display only indispensable information on the screen.As a result, design error due to missing of the undercut, etc. can beprevented.

[0133] In this event, for instance, candidates of the split borderlinewould be selected by forming a flat surface perpendicular to the moldopening direction, then projecting the product shape onto the flatsurface so as to detect its outermost peripheral line, and then drawinga straight line from the outermost peripheral line in the mold openingdirection so as to detect entire borderlines of the product shape beingintersecting with this straight line. In general, the split line(parting line) would often be obtained as an outermost peripheralcontour of the product shape viewed in the mold opening direction. Withthe above method, the split line may be determined readily by detectingthe candidates of the split borderline.

[0134] As for the second design method of the present invention, in theinjection mold design method for designing the core and the cavity bycorrecting the profile of the product to be fabricated into a releasableprofile from the mold, then arranging the corrected product shape in themold block being displayed on the screen to provide a cavitycorresponding to the product shape in the mold block, and then splittingthe mold block, the undercut portion may be detected by calculating anormal vector on the plane of the product shape and a reference vectorin the mold opening direction, and then detecting a normal vector havingthe opposite direction to that of the reference vector.

[0135] According to the second design method of the present invention,the undercut portion may be detected by comparing the normal vector onthe plane of the product shape and the reference vector in the moldopening direction, and then detecting the normal vector with theopposite direction to that of the reference vector. In other words, theplane with the normal vector having the opposite direction to that ofthe reference vector always exists in the undercut portion. In thepresent invention, the undercut portion can be automatically detectedbased on such a characteristic. As for the third design method of thepresent invention, in the injection mold design method for designing thecore and the cavity by correcting the profile of the product to befabricated into a releasable profile from the mold, then arranging thecorrected product shape in the mold block being displayed on the screento provide a cavity corresponding to the product shape in the moldblock, and then splitting the mold block, the split plane may be formedby extending the designated split borderline in parallel to thedesignated direction when the mold block is split into the core and thecavity.

[0136] As for the fourth design method of the present invention, in theinjection mold design method for designing the core and the cavity bycorrecting the profile of the product to be fabricated into a releasableprofile from the mold, then arranging the corrected product shape in themold block being displayed on the screen to provide a cavitycorresponding to the product shape in the mold block, and then splittingthe mold block, candidates of the split line for splitting the core ofthe mold block into the nest structure may be selected by detecting-abottom of the cavity in the core side, and then extending a peripheralportion of the bottom along the mold opening direction.

[0137] According to the fourth design method of the present invention,when forming the nest structure, the candidates of the split line forsplitting the core of the mold block into the nest structure may beselected by detecting the bottom of the cavity in the core side, andthen extending the peripheral portion of the bottom in the mold openingdirection. Subsequently, by way of example, the candidates of the splitline are numbered in the order from near side of an arbitrary point,then the core may be split by employing odd numbered or even numbered(either one being selected by the designer) candidates of the split lineas the split line, and then the split portion may be determined finallyas the nest structure. In this manner, the nest structure may beautomatically designed.

[0138] Next, preferred embodiments of the present invention will beexplained with reference to accompanying drawings. FIGS. 2 to 81Fillustrates an injection mold design system and an injection mold designmethod according to embodiments of the present invention.

[0139]FIG. 2 shows a configuration of a plastics injection mold designsystem according to an embodiment of the present invention. In FIG. 2, areference 11 denotes a design data memory (storing means) for storingproduct shape data (image information) D1 to display a stereoscopicdrawing and a projection drawing of a product to be fabricated. Data D1are binary data.

[0140] A reference 12 denotes a base file for storing mold base data D2as a database which may store profiles of cavity and core parts, platesto which cavity and core parts are clamped, regular parts (screw,ejector pin, water cooling path, etc.), and the like.

[0141] A reference 13 denotes a work memory for storing imageinformation (data D1 to D6, etc.) of a mold model and a product modelgenerated in the course of design operation. D3 are element data such asline elements of the product (i.e., data such as length, curvature,angle of lines constituting the product shape) and plane elements of theproduct (i.e., data such as size, curvature, angle of planesconstituting the product shape). D4 are cavity/core data for definingshapes of the cavity and the core. D5 are image data required fordisplay on a display 19. D6 are input data such as control statement,etc.

[0142] A reference 14 denotes a product shape correction editor forexecuting correction operation of the product shape so as to enable theproduct to be stripped off readily from the mold, and the like. Theproduct shape correction editor 14 comprises, as respective softwares, aparting line forming section 41, a draft-sloped plane providing section42, a shrinkage rate correction section 43, and the like. The partingline forming section 41 may serve to extract candidates of the partingline from product shape data D1, form the parting line, detect theundercut portion residing in the product shape, edit the parting line(i.e., rearrange the parting lines having continuous locationcoordinates into same groups), and check loops of the parting lines. Thedraft-sloped plane providing section 42 may serve to detect respectiveplanes which are to be sloped for easy drafting of the product from themold and respective planes which are preferably to be sloped (theseplanes being referred to as “sloped planes” hereinafter), provide thedraft slope to the detected sloped planes, and check whether or not theproduct may be released readily from the mold. The shrinkage ratecorrection section 43 may serve to examine changes of respectivedimensions of the product according to the shrinkage rate caused whenthe resin cures in the mold, and detect the portions of the product, forexample, which cannot be drafted from the core because convex portionsof the core are put into the product. If such portions have beendetected, required treatments are effected such that the profile of themold must be modified partially, the draft slope must be provided toconcerned planes by the draft-sloped plane providing section 42, or thelike.

[0143] A reference 15 denotes a cavity design editor for designing thecavity in the mold. The cavity design editor 15 comprises, as respectivesoftwares, a cavity/core arranging section 51, a mold splitting section52 including a slide split section 501 and a nest split section 502, andthe like. The cavity/core arranging section 51 may generate a mold blocksuch as rectangular parallelepiped or circular cylinder each havinglarger profile than that of the product shape on the screen, and thenform a cavity with a profile identical to the product shape in the moldblock. The mold splitting section 52 may form a main parting planeaccording to the parting line candidates which are extracted by theforegoing parting line forming section 41, and generate the cavity andthe core on the screen by splitting the mold block by the main partingplane. The slide split section 501 may function to form a slide planebeing used to split the cavity or the core to form the undercut portionas a slide structure, and check interference between the cavity and thecore. Furthermore, the nest split section 502 may generate the partingline for forming nests on the core side depending upon a depth of themold, provide priority levels to respective parting lines for splittingthe core, and form nests by splitting the core.

[0144] A reference 16 denotes a plate design editor for designingconstituent parts necessary for the mold. The plate design editor 16comprises, as respective softwares, a mold base arranging section 61, agate design section 62, a runner design section 63, a sprue designsection 64, a gas vent design section 65, an ejector pin design section66, a temperature adjusting structure design section 67, a movablestructure design section 68, and so on. The mold base arranging section61 may design portions for fixing the mold such as the mold base. Thegate design section 62 may also design location, shape, size, etc. ofthe gates. The runner design section 63 may further design shape,location, etc. of the runners to introduce the resin to the mold in thelateral direction thereof. In addition, the sprue design section 64 maydesign shape, location, etc. of the sprue (sprue runner) to introducethe resin to the runner in the vertical direction of the injectionmolding machine. The gas vent design section 65 may design shape,location, size, etc. of the gas vent to exhaust the air from the moldwhen the resin being injected into the mold. The ejector pin designsection 66 may design shape, location, etc. of the ejector pin to ejectthe moldings from the mold. The temperature adjusting structure designsection 67 may design the cooling path to cool the mold. Finally, themovable structure design section 68 may design driving systems (linkmechanism) such as runner stripper plate, cavity plate, and core plate.

[0145] A reference 17 denotes a keyboard (input means) for inputtingcontrol statement etc. to the concerned design system as input data(designation information) D6 by the designer, and instructing switchingof the screen. Auxiliary input tool such as a mouse may be connected tothe keyboard 17. The product or the mold on the screen may be rotated byoperating the mouse or the ten key.

[0146] A reference 18 denotes a CPU (Central Processing Unit) forcontrolling input/output of design data memory 11, base file 12, workmemory 13, product shape correction editor 14, cavity design editor 15,plate design editor 16, keyboard 17, display 19, printer 20, and othermemory 21. Depending upon designation information input through thekeyboard 17, the CPU 18 may execute various functions for temporarilyunloading data of lines or planes, which being obstructive to thecorrection operation of the product shape or the mold operationcurrently displayed on the screen, to the work memory 13, then removingthe lines or planes from the screen, and then replotting the lines orplanes on the screen after the correction operation of the product shapeor the mold profile being completed.

[0147] The CPU 18 further causes the work memory 13 to store historicalfile generated in respective design operations. For instance, the CPU 18stores in time sequence five historical files of data generated in therespective function editors into the work memory 13 in the order fromNo.1 to No.5. In this event, on the assumptions that forming data of thefillet (i.e., reinforce member provided on the intersecting portionbetween more than two planes) data are stored into the historical fileNo.3, that data for providing the draft slope are stored into thehistorical file No.5, and that in addition it is hard to provide thedraft slope because the fillet serves as the obstruction, the CPU 18returns to the historical file No.3 prior to forming the fillet and thenprovides the draft slope using data stored in the historical file No.5to the concerned plane. Subsequently, the CPU 18 returns automaticallyto the historical file No.5 by using data stored in the historical filesNo.3 and No.4.

[0148] A reference 19 denotes a display (displaying means) fordisplaying the product model or the mold two or three-dimensionally bymeans of reading image information from design data memory 11, databasememory 12, or work memory 13. The display 19 comprises CRT (Cathode RayTube), liquid crystal display, plasma display, or the like.

[0149] In order to make easy for the designer to recognize thestereoscopic profile of the product, the design system of the presentinvention lets the display 19 display a stereoscopic drawing (isometricdrawing, etc.) as shown in FIG. 3A, for example. Referring to FIG. 3A, areference 1 denotes an example of the product to be molded. In thisproduct 1, reinforcing rib 1A, bosses 1B to which parts such as printedcircuit board are fixed, holes 1C into which external terminals, etc.are inserted are provided.

[0150]FIG. 3B illustrates kinds of design drawings which are able to bedisplayed by the display 19. Where (1) is a top view of the product 1and FIG. 3C is a top view of the product 1, for example, (2) is a frontview of the product 1 and FIG. 3D is a front view of the product 1, forexample, (3) is a rear view of the product 1, (4) is a right side viewof the product 1, (5) is a left side view and FIG. 3E is a left sideview of the product 1, for example, (6) is a bottom view of the product1, (7) is a right front isometric view showing the product 1three-dimensionally, (8) is a left front isometric view of the same, (9)is a right rear isometric view of the same, and (10) is a left rearisometric view of the same.

[0151] With combining these ten kinds design drawings with each other,three-dimensional display screen (window screen) may be depictedtogether in the two-dimensional display screen (main screen) on thedisplay 19. More particularly, when draft slope, nest split, partingplane, gate, runner, ejector pin, and gas vent will be designed, any oneof isometric drawings (7) to (10) of the product 1 may be displayedsimultaneously with plan views of above (1) to (6) on the display 19.Besides, when cavity/core split, cooling path, and link will bedesigned, any one of isometric drawings (7) to (10) of the product 1 mayalso be displayed simultaneously with plan views of above (2) to (5) onthe display 19. In the present design system, these design drawings aredisplayed using three-dimensional CAD tool, CG (Computer Graphics) tool,etc.

[0152] Furthermore, the present design system may be equipped with afunction for removing temporarily from the screen lines or planes beingobstructive to the correction process upon correcting the product shape.For instance, when the profile of the product 1 will be corrected, afillet portion 1D of the product 1 in FIG. 3F may be removed from thescreen, and alternatively an isometric drawing as shown in FIG. 3G maybe displayed. When the correction operation has been completed, thefillet portion may be replotted on the screen.

[0153] A reference 20 denotes a printer for outputting profiles anddimensions of the mold parts on the paper.

[0154] A reference 21 denotes other memory. Various design items forsimplifying operations of the mold design system, configuration filesfor supporting the mold design system, and various default valuesrequired for design of the mold parts may be stored in this memory. Aread-only memory in which data are rewritable and erasable may be usedas the memory 21. EPROM and EEPROM are suitable for the memory 21. Thedesign items will be explained later in the twentieth embodiment.Operation of the configuration files will be explained later in thetwenty-sixth embodiment.

[0155] Next, an operation of the injection mold design system accordingto the embodiment of the present invention will be explained. First thedesigner has to read image information of the product 1 from the designdata memory 11 via the keyboard 17 to display the stereoscopic drawingor the projection drawing of either the product 1 or the mold on thedisplay 19. At this time, the designer may temporarily unload data oflines or planes being obstructive to the profile correction operation ofthe product 1 or the mold into the work memory 13 through the keyboardetc. to thus remove these lines or planes from the screen, and maytherefore display only necessary information obviously.

[0156] With the above process, while watching or monitoring the screenon which lines or planes indispensable to the profile correctionoperation are displayed, the designer may correct the profile of eitherthe product 1 or the mold.

[0157] In the event that the profile of the product 1 should becorrected, for example, the designer may first generate temporarily onthe screen a flat plane on which the profile of the product 1 isprojected, then set new straight lines or new curves on the flat plane,and then project the straight lines or new curves onto the product 1.The new straight lines or new curves projected onto the product 1 can beextracted as the candidates of the parting lines to split the mold blockinto the cavity and the core.

[0158] Furthermore, in the case that the profile of the product 1 shouldbe corrected, the designer may first generates temporarily on the screena flat plane on which the profile lines, edges or borderlines betweenplanes of the product 1 are projected, then set new profile lines, edgesor borderlines between plane elements of the product 1 on this flatplane, and then project onto the product 1 the profile lines, edges orborderlines between plane elements of the product 1 these being newlyset. The new profile lines, edges or borderlines between plane elementsprojected onto the product 1 are extracted as the candidates of theparting lines to split the mold block into the cavity and the core.

[0159] As stated earlier, if the candidates of the parting lines havebeen extracted preliminarily, the parting lines required for splittingthe mold block into the cavity and the core may be prepared based on theprofile lines, edges or borderlines between plane elements of theproduct 1 even when the profile of the product 1 must be modified in thecourse of design operation because of correction of shrinkage rate,provision of draft slope, or the like.

[0160] Under the condition where the stereoscopic drawing and theprojection drawing of the product 1 are being displayed on the display19, the designer may therefore execute correction of the profile,extraction of the parting line, provision of draft slope, etc. of theproduct 1 in an interactive fashion.

[0161] After the profile correction operation of the product 1 or themold model has been completed, the CPU 18 may plot lines or planes inresponse to the instruction from the designer, using data which havebeen unloaded into the work memory 13.

[0162] Subsequently, an injection mold design method of the presentinvention together with operations of the design system will beexplained with reference to FIGS. 2 to 81F. FIGS. 4A to 4C areflowcharts (main routine) illustrating design operations of theinjection mold. More detailed operations in respective steps will beexplained in embodiments described later.

[0163] In FIG. 4A, in step A1, candidates of a main parting line forsplitting the mold block into the core and the cavity may be firstextracted from the product shape in the parting line forming section 41in the product shape correction editor 14 (see a first embodiment).

[0164] In step A2, planes to be sloped are in turn detected from theproduct shape in the draft-sloped plane providing section 42 (see asecond embodiment).

[0165] In step A3, priority levels are then assigned to respectivedraft-sloped planes in the draft-sloped plane providing section 42 (seea third embodiment). Then, in step A4, draft slopes are provided to theproduct shape in the draft-sloped plane providing section 42 (see afourth embodiment).

[0166] In step A5, the main parting line is in turn formed based on thecandidates of the main parting line already extracted in step A1 in theparting line forming section 41 (see a fifth embodiment).

[0167] In step A6, loop check of the main parting line is then effectedin the parting line forming section 41 (see a sixth embodiment). At thistime, if the main parting line has not formed a closed loop (NG), thenthe process returns to step A5 so as to repeat formation of the mainparting line.

[0168] If the main parting line has not been formed as the closed loopin step A6 (GOOD), then the process advances to step A7 where theundercut portions are extracted from the product shape in the partingline forming section 41 (see a seventh embodiment).

[0169] Thereafter, the process proceeds to step A8 where the partingline for a slide structure is formed in the parting line forming section41. The parting line for the slide structure is required when theparting plane for splitting the undercut portions into nest parts wouldbe formed. Subsequently, in step A9, edit operation of the main partingline is executed. This edit operation of the main parting line iseffected when the main parting line would be changed accompanying withformation of parting lines for a slide core. Substantially, the sameprocess as in step A5 is executed in step A9.

[0170] In step A10, loop check of the main parting line is againeffected in the parting line forming section 41. If the main partingline has not formed a closed loop at this time (NG), then the processreturns to step A8 to form the parting line for the slide structureagain. If GOOD in step A10, the process advances to step A11.

[0171] In step A11, releasability of the product shape is checked in thedraft-sloped plane providing section 42 (see a eighth embodiment). Moreparticularly, ejector force of the ejector pin and shrinkage force ofthe product shape are compared with each other. If ejector force of theejector pin has been less than shrinkage force of the product shape(NG), the process returns to step A4 to repeat provision operation ofthe draft slope. If ejector force of the ejector pin has been in excessof shrinkage force of the product shape (YES), the process advances tostep A12.

[0172] In FIG. 4B, in step A12, shrinkage rate of the product shape maybe corrected in the shrinkage rate correction section 43. In otherwords, since individual resins have different shrinkage rates when beingsolidified, sometimes the draft slope must be set again according to theresins. In step A12, a deformation amount of the product shape may becalculated in compliance with shrinkage rate of the resin.

[0173] In step A13, the designer would then determines whether or notlocal modification of the product shape is required. If the productshape has been determined to be locally modified in step A13 (YES), theprocess proceeds step A14 so as to modify the profile of the product 1locally (new draft slope setting, etc.). On the contrary, if it has beendetermined that local modification of the product shape should not beeffected in step A13 (NO), the process proceeds step A15.

[0174] In step A15, the cavity/core arranging section 51 in the cavitydesign editor 15 commences formation of the mold block. In step A16, thecavity/core arranging section 51 then reads out product shape data D1from the work memory 13. In step A17, the product shape and the moldblock are then overlapped and displayed on the display 19.

[0175] Next, in step A18, size and profile of the mold block arechecked. If it has been judged by the designer that size and profile ofthe mold block is not appropriate (NO), the process advances step A19.In step A19, the cavity/core arranging section 51 modifies dimension ofthe mold block and displays modified dimension. Conversely, it has beendetermined in step A18 that size and profile of the mold block isappropriate (GOOD), the process advances step A20.

[0176] In step A20, a portion in the mold block corresponding to theproduct shape may be made hollow in the cavity/core arranging section51. The hollow portion of the product shape may be formed by invertingthe product shape portion and the hollow portion mutually (solid/hollowinverting function) in terms of Boolean operation which are executed inthe cavity/core arranging section 51. Cavity/ core data D4 obtained byBoolean operation which are executed in the cavity/core arrangingsection 51 are stored in the work memory 13. An isometric drawing asshown in FIG. 5 would be displayed on the display 19. In FIG. 5, areference 100 denotes the mold block, whereas a reference 100A denotesthe mold cavity portion.

[0177] In turn, in step A21 in FIG. 4C, the main parting plane forsplitting the mold block 100 may be formed in the mold splitting section52 (see a ninth embodiment).

[0178] Thereafter, in step A22, process for splitting the mold block 100into the cavity and the core may be started in the mold splittingsection 52, and then in step A23 the slide parting line may be formed.Then in step A24, a slide parting plane may be formed based on the slideparting line in the mold splitting section 52.

[0179] In step A25, the mold block 100 is divided into the cavity andthe core by providing the slide parting plane to the mold block 100 inthe slide split section 501. As shown in FIG. 6, an isometric drawing inwhich the cavity 3 and the core 4 are split is displayed on the display19.

[0180] Next, in step A26, it would be detected in the mold splittingsection 52 whether there is caused interference between the cavity 3 andthe core 4 or not (mold opening interference check). If it has beendetermined that mold opening is impossible due to interference betweenthe cavity 3 and the core 4 (NG), the process advances to step A27 whereedit of parting lines and parting planes is repeated in the moldsplitting section 52. If it has been determined that mold opening isfeasible because of no interference between the cavity 3 and the core 4(GOOD), the process advances to step A28. The mold opening interferencecheck is determined depending upon whether or not a coordinate value ofa certain line element is overlapped with other line element, or thelike.

[0181] Next, in step A28, the parting line for splitting the cavity 3 orthe core 4 (usually, core) is formed on the basis of depth of the moldin the nest split section 502. This is the case where the mold isconstituted with nests by splitting the cavity 3 or the core 4,therefore the nest structure would not be always required if the productshape is relatively simple.

[0182] In step A29, priority levels would be given to the parting linefor splitting into the nest in the nest split section 502. Then, in stepA30, the nest split section 502 may form the parting plane of the nest.

[0183] In the present embodiment, three kinds of structures such as flatplane locking structure shown in FIG. 7A, and socket and spigotstructure and positioning locking structure shown in FIG. 7B have beenprepared in advance as the parting plane of the nest. The designer maythus select one of these structures. Hence it would not be necessary forthe designer to input various data into the system, so that the nestparts for forming the undercut portion of the product 1 may be readilydesigned, and therefore a burden of the designer may be extremelyreduced.

[0184] In step A31, responding to instruction of the designer, part ofthe cavity 3 or the core 4 may be split into one or plural nests in thenest split section 502 (see tenth and eleventh embodiments). Forpurposes of example, with confirming the nests of the mold on theisometric drawing by the display 19, as shown in FIG. 8A, the designermay designate the sectional view of the nest. The designer theninstructs a split direction of the nest structure, as shown in FIG. 8B.Thereafter, before and after the nest structure is split as shown inFIG. 9A, the isometric drawing may be displayed on the display 19. Forthis reason, as shown in FIGS. 9B and 9C, three nest structures 1 to 3for splitting the core 4 by the parting plane are displayed on thedisplay 19. The top view of three nest structures 1 to 3 projected ontothe parting plane as well as the sectional view (FIG. 9B) of the nestmay be displayed on the display 19. In FIG. 9C, a hatched portion is adeepest plane of the mold. Likewise, the portion for forming boreportions, etc. of the product 1 may be constituted as the neststructure.

[0185] In step A32, the mold base for supporting the mold may bearranged in the mold base arranging section 61 of the plate designeditor 16 (see a twelfth embodiment).

[0186] Next, in step A33, a gate may be designed in the gate designsection 62 (see a thirteenth embodiment). In this event, since severalkinds of gate profiles have been stored in the database 12 aspatternized data in the present embodiment, the designer may then designthe gate by either selecting the kind of the gate or inputting numericvalues in compliance with procedures displayed on the screen.

[0187] In step A34, the runner may be designed in the runner designsection 63 (see a fourteenth embodiment). In this case, since severalkinds of runner profiles have also been stored in the database 12 aspatternized data in the present embodiment, the designer may design therunner by either selecting the kind of the runner or inputting numericvalues according to procedures displayed on the screen.

[0188] Subsequently, in step A35, the sprue may be designed in the spruedesign section 64. In this event, since several kinds of sprue profileshave been stored in the database 12 as patternized data in the presentembodiment, the designer may design the sprue by either selecting thekind of the sprue or inputting numeric values in compliance withprocedures displayed on the screen.

[0189] In step A36, the gas vent may be designed in the gas vent designsection 65 (see a fifteenth embodiment). In this case, since severalkinds of gas vent profiles have also been stored in the database 12 aspatternized data in the present embodiment, the designer may design thegas vent by either selecting the kind of the gas vent or inputtingnumeric values according to procedures displayed on the screen.

[0190] Furthermore, in step A37, profile, size, location of the ejectorpin and diameter of hole for the ejector pin provided in the core may bedesigned in the ejector pin design section 66 (see a sixteenthembodiment). In this event, since several kinds of ejector pin profiles,etc. have been stored in the database 12 as patternized data in thepresent embodiment, the designer may design the ejector pin by eitherselecting the kind of the ejector pin or inputting numeric values incompliance with procedures displayed on the screen.

[0191] In step A38, size, location, etc. of the cooling path may bedesigned in the temperature adjusting structure design section 67 (see aseventeenth embodiment). In the present embodiment, since several kindsof profiles, etc. of the cooling path are stored in the database 12 aspatternized data, the designer may design the cooling path by selectingkinds of the cooling path and inputting numerical values according toprocedures displayed on the screen.

[0192] In step A39, a “link structure” for coupling the runner stripperplate, cavity plate, and core plate may be designed in the movablestructure design section 68 (see an eighteenth embodiment). In thepresent embodiment, since several kinds of the link structures arestored in the database 12 as patternized data, the designer may designthe cooling path by selecting kinds of the link structure and inputtingnumerical values according to procedures displayed on the screen.

[0193] Consequently, it would be understood that the plastics injectionmold may be designed via respective steps of the main routine of thedesign system.

[0194] Next, respective function portions of the product shapecorrection editor 14, the cavity design editor 15 and the plate designeditor 16 in the design system according to the present invention willbe explained at every embodiment below.

[0195] (1) First Embodiment

[0196]FIG. 10 is a flowchart illustrating detection operation of profilelines of outermost periphery and though holes of the product accordingto the first embodiment of the present invention. In this process,candidates of the parting line may be extracted from the profile of theproduct 1 in the parting line forming section 41.

[0197] In step B1, the design system may first read the product shapedata D1 from the design data memory 11 and then display the productshape on the display 19 like as a stereoscopic display shown in FIG. 11.In step B2, the designer may input a mold opening direction of theproduct shape via the keyboard. The process then advances to step B3.The design system may then switch the display screen on the display 19to the top view, in which the product shape is viewed from the moldopening direction. The reason why the display should be switched to thetop view is that the parting line may often appear as the outermostperiphery of the product shape viewed from the mold opening direction.If the parting line detected in the top view is three-dimensionallydisplayed once again, it would become easy for the designer to monitorthe parting line. In the event that the mold opening direction cannot bedetermined as a certain direction, then the side view and the bottomview of the product 1 are displayed on the display 19.

[0198] In step B4, the top view being displayed on the display 19 may bedepicted as a shading display to clarify borderlines of the productshape. Where the shading display signifies color tone of the screen onthe display 19. For instance, insides of the profile line of the product1 are darkened and outside thereof are lightened on the display 19.

[0199] In step B5, data of the product shape may be binarized (i.e., adark portion on the screen is “0” whereas a light portion on the screenis “1”). Then, in step B6, dots constituting the profile line (referredto as “profile dots” hereinafter) may be detected. The borderlines asabove may be extracted by image processing using Laplacian filterdiscussed hereinafter.

[0200] In image processing using the Laplacian filter, values of fourpixels, i.e., upper, lower, right and left pixels B to E into which atarget pixel A displayed as the value “0” or “1” is fetched may be firstexamined. In the case of F<0 in the expression satisfyingF=(B+C+D+E)−4A, portions expressed by the value “1” show the borderlinesof the object side. In the case of F>0, portions expressed by the value“0” show the borderlines of the space side. In the case of F=0, there isno borderline. Consequently, according to this image processing, theprofile lines of the outermost periphery and through holes of theproduct 1 may be detected.

[0201] Then, in step B7, it is determined whether or not borderlines(edges) being placed directly beneath the profile lines previouslydetected may be detected. This edge detection may be effected by ascreen position function. The screen position function signifies that,for example, edges of side portions of the product shape are detected bydrawing lines from the plane (outermost periphery forming plane) on theproduct 1 downward in the vertical direction, as shown in FIG. 11. Ifthe edges have been detected (YES), then the process proceeds to step B8where it is checked whether the edges are detected for the first time.If the edges have been detected for the first time (YES), then theprocess advances to step B9. In step B9, individual identifiers (ID)indicating candidates of the parting lines are attached to edgeconstituting lines of the product shape data D1. Conversely, if theedges have been detected for the second time in step B8 (NO), theprocess then advances to step B12.

[0202] In step B10, display on the display 19 may be changed, and thenin step B11 line elements of candidates of the parting lines arerecorded in the work memory 13. In step B12, it is checked whether ornot succeeding candidates of the parting lines are therebelow. If thesucceeding candidates has existed (YES), then the process returns tostep B8. On the contrary, if there has been no succeeding candidate(NO), then the process advances to step B18.

[0203] While there has been no edge in step B7 (NO), the processadvances to step B13 where profile dots previously detected may beprojected onto the product shape.

[0204] In step B14, curves are formed on the surface of the productshape by the projected profile dots. Then in step B15, individualidentifiers (ID) are attached to the product shape data D1 as thecandidates of the parting lines.

[0205] Then in step B16, display on the display 19 may be changed. Instep B17, the candidates of the parting lines are stored in the workmemory 17, and the process then advances to step B18.

[0206] In step B18, it is checked whether or not succeeding profile dotsare present. If the profile dots have not been present (NO), the processis then terminated. While the profile dots have been present (YES), theprocess then returns to step B7 to repeat either steps B8 to B12 orsteps B8 to B17. As described above, as to all profile dots detectedfrom the top view, the candidates of the parting lines may be detected.Thus profile lines of the outermost periphery and the through holes ofthe product shape are extracted as edges or the borderlines of planepixels.

[0207] In this manner, in the injection mold design method according tothe first embodiment of the present invention, the candidates of severalparting lines may be preliminarily detected. Therefore, even if theproduct shape is modified in the middle of design operation because ofshrinkage rate correction or draft slope provision of the product 1, theparting lines being required for splitting the mold block into the coreand the cavity at desired location can be automatically obtained.

[0208] According to the first embodiment of the present invention, itwould be understood that, since the product shape beingthree-dimensionally displayed has been changed temporarily to thatviewed from the mold opening direction, the parting lines can be readilyextracted by detecting the outermost peripheral edge on the top view.Moreover, it would be apparent that, since the outer edge of the productshape may be displayed with different color from other portions on thedisplay 19 or since the product shape may be classified on the display19 by different color with defining the outer edge as the boundary, thedesigner may discriminate easily portions to which design process isrequested from portions to which design process is not requested.

[0209] (2) Second Embodiment

[0210]FIG. 12 is a flowchart illustrating detection process ofdraft-sloped planes according to the second embodiment of the presentinvention. In this process, planes to which draft slope should beprovided may be extracted from the product shape in the draft-slopedplane providing section 42.

[0211] First, in step C1, the product shape data D1 may be read from thedesign data memory 11. In step C2, plane elements of the product shapeare read out. The plane elements may correspond to bottom plane, sideplane, plane of rising portion of the product 1.

[0212] Then, in step C3, the designer may discriminate kinds of theplane elements. If a plane to be inspected has been a flat surface, theprocess proceeds to step C4 where center of gravity of the plane iscalculated. The process then advances to step C7.

[0213] If the plane to be inspected has been a free-form surface, thenthe process moves to step C5 where the designer may input the number ofgrid or the pitch of grid for splitting the free-form surface via thekeyboard 17. It should be noted that the number of grid or the pitch ofgrid may be set preliminarily in the design system.

[0214] After this, the CPU 18 may calculate coordinates of a gridintersecting point in step C6, and then the process moves to step C7.

[0215] In step C7, an inspection point identifier (ID) indicating aninspection point would be assigned to the center of gravity calculatedin step C4 or the grid intersecting point calculated in step C6. In stepC8, a unit normal vector is calculated on the inspection point. The unitnormal vector k derived here can be used as an inspection vector. Instep C9, the draft-sloped plane providing section 42 may assign theinspection point ID=k to the inspection point.

[0216] Thereafter, in step C10, components of the inspection vector k inthe mold opening direction may be examined. In case the inspectionvector k has been 0 (i.e., it is a parallel plane in the mold openingdirection), then the process proceeds to step C11. In step C11, usingthis plane as the sloped plane, a sloped plane identifier (ID) forindicating sloped plane would be assigned to the product shape data D1.In step C12, such sloped plane can be displayed with different colorfrom other planes on the display 19.

[0217] In step C13, a warning such as sound, display, etc. may be issuedto inform that the sloped plane has been detected. If in step C10 theinspection vector k has not been 0 (k≠0, i.e., it is a slant plane withrespect to the mold opening direction), it may be determined that theplane should not be sloped and then the process proceeds to step C14.

[0218] In step C14, it may be determined whether or not an inspectionpoint to be succeedingly tested is present. If the succeeding inspectionpoint has been present (YES), the process returns to step C7 where itmay be checked whether or not draft slope is needed. But if there hasbeen no succeeding inspection point in step C14 (NO), then the processadvances to step C20.

[0219] In the meanwhile, if the plane to be inspected is a circularcylinder surface in step C3, a unit vector k may be calculated for thecentral axis of the circular cylinder surface. The unit vector can beset as the inspection vector k.

[0220] In step C16, components of the inspection vector k in the moldopening direction may be examined. In case the inspection vector k hasbeen 1 (i.e., the central axis of the circular cylinder is parallel tothe mold opening direction), then the process proceeds to step C17. Instep C17, the sloped plane identifier (ID) for indicating the slopedplane may be assigned to data of the circular cylinder surface in theproduct shape data D1. In step C18, such sloped plane may be displayedwith different color from other planes on the display 19.

[0221] In step C19, it may be informed by sound, display, etc. that thesloped plane has been detected. If in step C14 the inspection vector khas not been 1 (k≠1, i.e., the central axis of the circular cylindersurface is perpendicular to the mold opening direction), it may bedetermined that the plane should not be sloped and then the processproceeds to step C20.

[0222] In step C20, it may be determined whether a plane to besucceedingly inspected is present or not. If the succeeding inspectionplane has been present (YES), then the process returns to step C2 wheresteps C2 to C14 are repeated. But if there has been no succeedinginspection plane (NO), then the process is terminated.

[0223] With the above processes, it would be obvious that, even if therising portion of the product shape has been formed by a flat surface, afree-form surface, or a circular cylinder surface, the sloped plane maybe detected. Such detected sloped plane would been stored in the workmemory 13 as element data D3.

[0224] (3) Third Embodiment

[0225]FIG. 13 is a flowchart illustrating assign process of prioritylevels to draft slopes according to the third embodiment of the presentinvention. In this process, priority levels may be assigned torespective sloped planes detected in the second embodiment in thedraft-sloped plane providing section 42.

[0226] In FIG. 13, in step D1, information of sloped plane previouslyregistered may be first read from the work memory 13. In step D2, amagnification center of the draft slope plane may then be calculated.The magnification center is a center of gravity of the product when theproduct shape is projected onto the flat plane being parallel to themold opening direction.

[0227] Subsequently, in step D3, the inspection vector k may becalculated before the magnification being effected. In step D4, theproduct shape may be magnified in the direction perpendicular to themold opening direction Z on the display 19. FIG. 14 is an isometricdrawing showing the product shape before and after the magnificationbeing conducted. Next, in step D5, the inspection vector is calculatedafter the magnification being effected.

[0228] In step D6, shrinkage vector as for the sloped plane may becalculated. FIG. 15A is a sectional view showing a certain edge of theproduct 1 before and after the magnification being executed. In FIG.15A, points (a) and (b) denote respectively a sample point of the edgeof the product 1 before and after the magnification being effected. FIG.15B shows a vector analysis chart of the point (a). S (where a vectorsymbol being omitted) means the shrinkage vector, and a vector componentsuch that the core may be clamped by the product. P (where a vectorsymbol also being omitted) means the normal vector of the edge plane. Ps(where a vector symbol also being omitted) means the normal vector ofthe edge plane of the product 1 in the shrinkage direction (referred toas “normal vector in the shrinkage direction” hereinafter). In case theshrinkage vector S and the normal vector Ps in the shrinkage directionare opposite to each other (i.e., if it is an outer plane), the moldingsbe able to be easily released from the mold. Therefore this indicatesthat the edge plane need not be draft-sloped (but it would be preferableto provide the draft slope).

[0229]FIG. 15C shows a vector analysis chart of the point (b). In casethe shrinkage vector S and the normal vector Ps in the shrinkagedirection are in the same direction (i.e., if it is an inner plane), themoldings cannot be readily released from the mold. Therefore thisindicates that the draft slope must always be given to the edge plane.

[0230] In other words, in step D7, components of the sample points (a)and (b) in the magnification center direction may be detected from theenlarged view of draft-sloped plane as shown in FIG. 15A. In step D8,vector analysis may be effected on the sample points (a) and (b). On theother hand, if the shrinkage vector S and the normal vector Ps in theshrinkage direction have been in the opposite direction (NO), theprocess advances to step D11 where necessity of the draft slope may berecorded. Then in step D12, a warning to the effect that provision ofthe draft slope is not indispensable but preferable may be displayed onthe display 19.

[0231] In step D8, in case both directions of the shrinkage vector S andthe normal vector Ps in the shrinkage direction have coincided with eachother (YES), the process advances to step D9 where indispensablenecessity of the draft slope may be recorded. Then in step D12, awarning to the effect that provision of the draft slope is indispensablemay be displayed on the display 19.

[0232] Consequently, depending on the shrinkage vector S and the normalvector Ps in the shrinkage direction, constituent planes of the product1 may be classified into the planes to which the draft slope isindispensable and the planes to which the draft slope is preferable.

[0233] As discussed earlier, according to the injection mold designmethod of the third embodiment of the present invention, it may beconfirmed whether or not the draft slope is appropriately provided toportions, to which the draft slope is indispensable, by comparing bothdirections of the shrinkage vector S and the normal vector Ps of thesloped plane of the product shape. This is because priority levels havebeen assigned to “the plane to which the slope plane of the mold isindispensable” in step D9 and “the plane which is preferable to beformed as the slope plane” in step D11.

[0234] (4) Fourth Embodiment

[0235]FIG. 16 is a flowchart illustrating provision process of draftslope according to the fourth embodiment of the present invention. Inthis process, slant may be given to the draft-sloped plane by thedraft-sloped plane providing section 42. As the method for providing theslant, a method for simply inclining the sloped plane, a method forutilizing a slant plane of circular cone, and a method for forming aruled plane which being formed by connecting a shifted base side edge ofthe rising plane and a leading edge of the same by shifting the baseside edge at a distance in the horizontal direction may be listed.

[0236] In FIG. 16, in step E1, element data D3 of edge in the productshape previously recorded are first read out from the work memory 13.

[0237] Then in step E2, the designer may select a sloped plane. If theselected plane is a flat plane, the process advances to step E3 where,as shown in a broken line circle in FIG. 17, the sectional view of theedge of the product 1 may be temporarily displayed on the display 19. Inthe broken line circle in FIG. 17, a guide curve (reference line) isdisplayed along the edge of the product shape on the display 19. In FIG.17, the designer may set a reference point at an arbitrary location onthe edge line of the product shape, and extend the reference point fromthe reference point in the X or Y direction of the product shape.

[0238] In steps E4 and E5, the designer may input angle and rotationdirection through the keyboard. The process may move to step E6 where,as shown in FIG. 17, the designer may rotate the edge plane of theproduct shape by input angle in the input rotation direction with theguide curve as the center to thus form a new plane. Thus a sloped planecan be derived.

[0239] As shown in FIG. 18, a new edge may be selected and projectedonto the product shape. In FIG. 18, a reference 1E denotes an originaledge portion, and a reference 1F denotes a edge portion after offset iseffected by projecting onto the product 1. The isometric drawing of theproduct shape to which the draft slope as shown in FIG. 19 beingprovided may be displayed on the display 19. Then the process advancesto step E17.

[0240] Instead, in step E2, if the rising portion of the product shapehas been formed by the free-form surface, the process proceeds to stepE7 where the guide curve (reference line) may be formed to generate theruled plane. At this time, a cross section of the edge may be displayedtemporarily as the plan view on the display 19. The cross section of theedge is the rising portion of the product 1. The plan view intersectsperpendicularly with the guide curve.

[0241] In the next, in step E8, the edge may be projected to the planview on the display 19. In step E9, the designer inputs an offset amountof the base side edge of the rising plane. In step E10, the designsystem may then project the offset edge to the product shape.

[0242] In step E11, a triangle can be created with setting offset edge,not-offset edge, and top edge of the rising plane as its three apexes.Then locus of oblique sides of the triangle may be created by moving thetriangle along the guide curve to obtain a ruled plane. The processproceeds to step E17.

[0243] Alternatively, in the event that in step E2 formation of a ruledplane by using a circular cone surface has been selected, the processmoves to step E12 where a reference line (guide curve) may be created toform the ruled plane. In step E13 and E14, the designer may input angleof the circular cone and intersecting line calculating pitch. Inresponse to this input, in step E15, the design system may shift thecircular cone along the reference line. Then, for respectiveintersecting line calculating pitches, it may calculate intersectinglines between locus of the oblique side of the circular cone or aprolonged line of the oblique side and the bottom.

[0244] Then in step E16, the design system may form the ruled plane forconnecting the calculated intersecting lines to the top edge of therising plane. Then the process advances to step E17. This method forforming the ruled plane by using the circular cone may be applicableeven if the bottom is not the flat plane. The intersecting lines may beutilized when the profile would be further corrected in post-process.

[0245] In step E17, connecting portion of the ruled plane is processed.In other words, intersecting lines of the ruled plane in the portion towhich a plurality of planes being connected may be calculated, andoverlapped portions of the ruled plane may then be trimmed. As above, incase the rising portion of the product shape is either the flat surfaceor the free-form surface or unless the bottom is the flat plane, slant(draft slope) may be provided to the product shape. Information as tothe draft slope of the product shape are stored into the work memory 13.

[0246] In the mold design method according to the fourth embodiment ofthe present invention, the reference point being newly designated on theflat surface temporarily formed in step E2 may be projected onto therising portion of the product shape, then the guide curve may be createdby extending the new reference point, and then the sloped plane may beformed by inclining the plane or moving the circular cone along theguide curve. The draft slope may therefore be provided to the risingplane of the product shape.

[0247] Hence, it would be understood that, if the sloped plane ismodified according to shrinkage rate correction of the product shape,the slope may be freely modified by assigning angle of the oblique sideof the circular cone again, etc. For this reason, the sloped plane beingsuitable for the product shape may be provided. The best sloped planeenables the product 1 to be released readily from the mold.

[0248] In the conventional three-dimensional CAD system, only thefunction for giving a slope to flat surface or circular cylinder surfacemay be effected, but in the fourth embodiment of the present inventionthe best sloped plane may be provided to the product 1, as illustratedin steps E7 to E11 or steps E12 to E14, even if the sloped plane isformed of the curve line. As a result, in the fourth embodiment of thepresent invention, in case the sloped plane of the free-form surfaceshould be modified because of the shrinkage rate correction of theproduct 1, the sloped plane may be modified arbitrarily by setting a newedge on the temporarily formed flat plane. Thus the best sloped planemay be provided when the profile of the product 1 has been changed.

[0249] (5) Fifth Embodiment

[0250]FIG. 20 is a flowchart for forming the parting line according tothe fifth embodiment of the present invention. In this process, the mainparting line for splitting the mold into the cavity and the core may beformed in the parting line forming section 41. In the fifth embodimentof the present invention, steps Fl to F3 and steps F11 to F14 overlapwith other embodiments.

[0251] In FIG. 20, in step F1, candidates of the parting line may firstbe extracted as shown previously in FIG. 10 and, in step F2, partingline candidate IDs are assigned to respective candidates of the partingline. The process then proceeds to step F3 where the draft slope may beprovided in the manner as shown previously in FIG. 17.

[0252] Next, in step F4, the guide curve (reference line) used toprovide the draft slope may also be supplemented as the candidates ofthe parting line. This is because the guide curve would be required forprofile correction, etc. of the product 1.

[0253] In step F5, the candidates of the parting line may be read fromthe work memory 13. In step F6, it may be determined by the designerwhether or not the candidates of the parting line should be used as themain parting line. If the candidates of the parting line have been usedas the main parting line (YES), the process then advances to step F7.Where the line element may be registered as the main parting line in thework memory 13.

[0254] At this time, if the edge cannot be designated because theproduct shape is formed of the circular cylinder as shown in FIG. 21A orif the parting line should be provided on the portion other than theedge, the designer may first define a flat plane perpendicular to anormal line on the parting line forming plane (curve forming plane). Acurve (or straight line) may be formed on this plane. The design systemthen projects the curve (or straight line) onto the circular cylindershape product shape. Consequently, as shown in FIG. 21B, the partingline may be formed on the product shape 1 with a circular cylindershape.

[0255] After the main parting line being set and the line elements beingrecorded, as above, the designer may cause the display 19 to display theproduct shape (bottom view) viewed in the mold opening direction, asshown in FIG. 22, to designate an outer edge. Thus the display 19 maydisplay such that color tone of the designated outer edge portion has tobe changed, inside and outside with the outer edge as the boundary haveto be displayed by different kind of line, or silhouette has to bechanged in inside/outside of the parting line (marking process).

[0256] In step F8, parting line IDs for indicating that the lineelements being used as the main parting line are assigned to the lineelements. In step F9, display on the display 19 may then be changed(marking process) so as to discriminate the concerned line elements fromother lines, and the process advances to step F10.

[0257] On the other hand, if the designer has determined that thecandidates are not used as the main parting line in step F6 (NO), thenin step F10 it is retrieved whether or not succeeding candidates arepresent. If there has been succeeding candidates (YES), then the processreturns to step F5 to repeat steps F5 to F10. If there has been nosucceeding candidate (NO), then the process advances to step F11 whereloop check may be effected to check whether the main parting line can beformed as a closed loop.

[0258] Unless the main parting line could be formed as the closed loop(YES), then in step F12 it may be corrected. With monitoring the display19, the designer may correct the main parting line by indicating edgecurve, borderline, etc.

[0259] Thereafter, the process then proceeds to step F13 where theparting line IDs are assigned to edited parting line. In step F14, thedisplay 19 may change the display on the screen. Then the processreturns to step F11.

[0260] In the event that there has been no open element (NO), setting ofthe main parting line may be ended. Element data D3 of the main partingline being set are stored in the work memory 13. Consequently, the mainparting line for splitting the mold into the cavity and core has beenformed.

[0261] Like the above, according to the mold design method according tothe fifth embodiment of the present invention, it would be evident that,as shown in step F7, the projection plane may be defined on theperpendicular plane to the normal direction of the curved surface of thecircular cylinder shape, and the straight line may be formed on thisplane, and then the straight line may be projected onto the curvedsurface of the product. Therefore, the mold design method would beconvenient when the edge cannot be designated to the curved surface orwhen the parting line has to be formed on the portion other than theedge. Furthermore, if the main parting line must be raised intentionallyfrom the plane of the product in the mold opening direction, the partingline may be designed arbitrarily by forming the parting line on the topview of the product and then projecting it onto the side view of theproduct.

[0262] (6) Sixth Embodiment

[0263]FIG. 23 is a flowchart illustrating check process of the partingline according to the sixth embodiment of the present invention. In thisprocess, it may be checked automatically whether or not the main partingline is formed as the closed loop in the parting line forming section41. If OK, it would be set as the parting line.

[0264] In FIG. 23, in step G1, element data of the parting lines mayfirst be read from the work memory 13. In step G2, loop check of theparting lines may be commenced. The designer may designate the elementof the parting lines to start loop check. As shown in FIG. 24, theelements of the parting lines are labelled by ePL(n).

[0265] Then, in step G3, as for the elements of the parting linesdesignated by the designer, the loop numbers are assigned to the partinglines, and in step G4 coordinates of a starting point knot may becalculated. The parting lines assigned by the loop number are collectedinto a group as an element. Coordinates of starting point of the partinglines are given by (xn^(s), yn^(s), zn^(s)) and coordinates of end pointof the parting lines are given by (xn^(E), yn^(E), zn^(E)).

[0266] In step G5, elements ePL(n) of other parting lines connected toobject parting line may be retrieved. Then, in step G6, it may bedecided whether or not there are elements of the parting lines havingknots on the same coordinates. That is, it may be detected whetherstarting points of the elements ePL(n) coincide with end points of theelements ePL(n−1), or whether end points of the elements ePL(n) coincidewith starting points of the elements ePL(n+1).

[0267] In case it has been determined that there are elements of theparting lines having knots on the same coordinates (YES), then theprocess advances to step G7. In step G7, it may be determined whether ornot they are starting point knots of the parting lines. If they havebeen determined to be the starting point knots (YES), then in step G8 itwould be decided whether the succeeding loop number exists or not. Ifthe succeeding loop number has existed (YES), then in step G9 elementdata D3 of the parting lines having the succeeding loop number may beread out.

[0268] Then, returning to step G4, coordinates of the starting pointknots may be calculated. While, if it has been decided that there is noparting line having knots on the same coordinates in step G6 (NO), thenin step G10 elements of the parting lines being connected to otherparting lines are displayed.

[0269] In step G11, it may be decided whether or not plural elementsbeing connected to other parting lines are present. In case the numberof element has been decided as a plural (YES), then in step G12 whereother parting lines are checked. The designer may designate elements ofthe parting lines to be checked at this time. For the parting linesdesignated by the designer, it may be judged in step G13 whether or notloop number of the designated parting lines is existing one. If the loopnumber of the designated parting lines has been decided to be existingone (YES), then the process moves to step G15. Conversely, if it hasbeen decided that the loop number of the designated parting lines is notexisting one (NO), then in step G14 loop numbers are assigned tonon-selected parting lines. Then in step G15, coordinate values ofsucceeding knots may be calculated.

[0270] Thereafter, returning to step G5, elements of the parting linesbeing connected to other parting lines are retrieved. In step G6, it maybe decided whether or not there are elements of the parting lines havingknots on the same coordinates. In case it has been determined that thereis no element of the parting lines having knots on the same coordinates,i.e., that the parting line does not constitute a closed loop (NO), thenthe process advances to step G16. An error message is displayed on thedisplay 19, then the process goes to step G17 where abnormal terminationis effected.

[0271] In step G8, if it has been determined that there is no succeedingloop number (NO), then in step G18 it may be examined whether elementsof unchecked parting lines exist or not. If there have been elements ofunchecked parting lines (YES), the process returns to step G3 to repeatsteps G3 to G15 etc. If there has been no unchecked parting lines (NO),the process may be terminated since all grouped parting lines have beenformed respectively as closed loops. Thus check of the parting lines hasbeen completed.

[0272] As has been stated above, in the mold design method according tothe sixth embodiment of the present invention, by checking in step G6according to the coordinate retrieval result of line elements of theparting lines whether there are elements of the parting lines havingknots on the same coordinates, it may be checked automatically whetheror not the parting lines may constitute the closed loop. Therefore, ifthe parting lines have been formed as the closed loop, it can be graspedin the initial stage of design that “the mold block 100 can be splitinto the cavity and the core”, whereas if the parting lines have notbeen formed as the closed loop, it can be found in the initial stage ofdesign that “the mold block 100 cannot be split into the cavity and thecore”. Overlapping of line elements of the parting lines may be checkedby the check function.

[0273] According to the sixth embodiment of the present invention, itwould be evident that line elements of the parting lines may be groupedby allotting loop number to the line elements of the parting lines instep G3. Hence, batch data processing may be effected when the splitplane for splitting the mold block 100 into the cavity and the core isformed, or when individual identifiers (IDs) such as priority level areassigned.

[0274] (7) Seventh Embodiment

[0275]FIG. 25 is a flowchart for detecting undercut portions in theproduct shape according to the seventh embodiment of the presentinvention. In this process, the parting lines constituting the openingportion (hole) of the product 1 in the parting line forming section 41.In the mold, the undercut portion may be formed as a nest structure. Inthe nest structure, the moldings must be released from the mold bysliding the split portions.

[0276] In FIG. 25, in step H1, product shape data D1 to which the mainparting line has been determined may first be read from the work memory13. In step H2, the direction of retrieval vector for retrieving theundercut may be set.

[0277] As shown in FIG. 26, the retrieval vector is −Z component, whichis opposite direction to the vector in the mold opening direction. Themold opening direction may be defined as the direction for splitting themold block 100 into the cavity and the core (see FIG. 5). Accordingly,the plane elements having their normal vectors in the same direction asthe retrieval vector become obstructive when the mold block 100 is splitinto the cavity and the core.

[0278] In step H3, plane elements constituting the product shape may beread out, and in step H4 components of the normal vector on the productplane with respect to the retrieval vector may be examined. As shown inFIG. 26, if the normal vector is opposite to the direction component ofthe retrieval vector, i.e., positive (+) or if it is 0, the progressgoes to step H10 where succeeding plane elements are retrieved since itis not obstructive to the mold opening. As shown in FIG. 27, the openinghole on the upper surface of the product 1 with the direction of itsretrieval vector of 0 is not the undercut portion. In order todiscriminate such opening portion from the undercut portion, the openingportion may be displayed with different color tone on the display 19.

[0279] If the normal vector is identical to the direction component ofthe retrieval vector, i.e., negative (−), the process advances to stepH5. For instance, the designer may input the number of grid to split theplane since as shown in FIG. 26 the undercut portion being obstructiveto the mold opening is present. In step H6, the CPU 18 may calculategrid intersecting points including parting lines of the plane serving asthe undercut portion.

[0280] In step H7, straight lines (semi-infinite straight lines) whichextend in the (−) direction of the retrieval vector using the gridintersecting points as the starting points are formed. In step H8, itmay be detected whether product planes intersecting with thesesemi-infinite straight lines exist or not. If there have been productplanes intersecting with the semi-infinite straight lines (YES), theprocess proceeds to step H9 where they can be registered as the undercutportions. Undercut IDs are assigned to the product shape data D1.

[0281] Unless product plane intersecting with the semi-infinite straightlines has been detected in step H8 (NO), no undercut portion can beregistered. The process then goes to step H10 where it is checkedwhether or not plane elements to be succeedingly inspected are present.If there have been plane elements to be succeedingly inspected (YES),the process returns to step H3. Plane elements constituting the productshape may then be read out. Steps H3 to H9 may then be repeated. In stepH10, if there has been no plane element to be succeedingly inspected(NO), the process may be ended. As a result, the undercut portions ofthe product 1 may be detected.

[0282] In this manner, in the mold design method according to theseventh embodiment of the present invention, the undercut portions beingobstructive to release of the cavity 3 from the core 4 of the mold maybe detected by retrieving the normal vector of the product shape in thesame direction as the retrieval vector. Thus, the rising portions of theproduct shape, the undercut hidden behind the boss, etc. cannot bemissed. By detecting the undercut, the core of the mold may be designedas the nest structure.

[0283] In addition, according to the seventh embodiment of the presentinvention, it would be obvious that, if the closed loop of other partingline is on the inside of the closed loop of a certain parting line, theclosed loop candidate of this inner parting line then shows the holeprovided in the product 1 other than the undercut portion. Therefore,the mold can be designed without escaping the rising portions of theproduct shape, the undercut hidden behind the boss, etc.

[0284] (8) Eighth Embodiment

[0285]FIGS. 28A and 28B are flowcharts illustrating check process ofreleasability of the draft-sloped plane according to the eighthembodiment of the present invention. In this process, it may be checkedin the draft-sloped plane providing section 42 whether or not themoldings can be easily released from the mold.

[0286] In FIG. 28A, in step I1 the product shape data D1 are read fromthe design data memory 11. In step 12 the plane elements of the productshape are read from the work memory 13. The designer may designate theplane element of the parting lines. The plane element can be selectedfrom flat surface, free-form surface, and circular cone surface.

[0287] In step 13, the plane element derived previously in FIGS. 3C to3E may be classified. If the plane element is the flat surface, then instep I4 where inspection points may be read.

[0288] In step I5, the shrinkage vector may be read, and then in step I6an area may be calculated. In step I7, shrinkage force caused upondrafting the moldings may be calculated by multiplying dimension andarea of the shrinkage vector together.

[0289] On the contrary, if the plane element is the free-form surface instep I3, then in step I8 the inspection point may be read, followed byreading of the shrinkage vector in step I9. Subsequently, in step I11,like the case where the plane element is the flat plane, the shrinkageforce may be calculated by multiplying dimension and area of theshrinkage vector together.

[0290] In step I12, it would be checked whether or not a succeedinginspection point is present. If it has been judged that the succeedinginspection point is present (YES), then the process returns to step I8so as to read the inspection point. If it has been judged that thesucceeding inspection point is not present (NO), then the process goesto step I13 where the shrinkage forces of the product 1 are summedentirely. The process proceeds to step I18.

[0291] Furthermore, if the plane element is the circular cone surface instep I3, then in step I14 the shrinkage vector may be read, thereafterin step I15 the area may be calculated. Next, in step I16, the shrinkageforce may be calculated by multiplying dimension and area of theshrinkage vector together. In step I17, whole shrinkage forces aresummed and the process goes to step I18.

[0292] In step I18, it may be decided whether succeeding plane elementis present or not. If the succeeding plane element has been present(YES), then the process returns to step I2 so as to repeat steps I3 toI18. Unless there has been the succeeding element in step I18 (NO), thenin step I19 stick strength of the moldings to the mold may be calculatedby multiplying the total shrinkage force by a certain coefficient.

[0293] After this, in step I20, ejector force of the ejector pin andstick strength of the moldings are compared with each other. In theevent that ejector force of the ejector pin has been less than stickstrength of the moldings (NO), the process then returns to draft slopestep of the main routine in FIG. 4A.

[0294] In the event that in step I20 ejector force of the ejector pinhas been more than stick strength of the moldings (YES), the processthen goes to step I22 where total shrinkage force of the core plane maybe calculated. Then in step I23, total shrinkage force of the cavityplane may be calculated.

[0295] In step I24, the total shrinkage force of the core plane and thetotal shrinkage force of the cavity plane may be compared with eachother. In case the total shrinkage force of the core plane has beenlarger than the total shrinkage force of the cavity plane (YES), theprocess may be terminated. On the contrary, in case the total shrinkageforce of the core plane has been smaller than the total shrinkage forceof the cavity plane (NO), the process then returns to draft slopprovision step I4 in the main routine in FIG. 4A so as to form the draftslope once more.

[0296] With the above processes, it would be apparent that it may bechecked whether or not the moldings can be easily released from the mold(i.e., releasability of the draft-sloped plane may be checked).

[0297] (9) Ninth Embodiment

[0298]FIGS. 29A to 29C are flowcharts illustrating formation process ofthe parting plane according to the ninth embodiment of the presentinvention. In this process, in the mold splitting section 52, the moldblock 100 may be formed to surround the product shapethree-dimensionally and then the cavity corresponding to the productshape may be formed in the mold block 100. A parting line plane 200 maybe formed based on the candidates of the parting lines, and then themold block 100 may be split based on the parting line plane 200 to formthe cavity and the core.

[0299] In FIG. 29A, in step J1, the cavity/core data D4 in which theactual product shape and the space profile to enclose the actual productshape are inverted may be read from the work memory 13. In step J2, theelement data D3 of the parting lines may be read from the work memory13.

[0300] In step J3, the designer may classify the mold block 100. Forpurposes of example, if the mold block 100 is the rectangularparallelepiped as shown in FIG. 30A, then in step J4, according to theinstruction from the designer, a coordinate system may be definedwherein a Z axis is the mold opening direction, an X axis is a longerside and a Y axis is a shorter side.

[0301] In step J5, it may be detected whether or not the parting linewhich intersects with the plane having the element X=0 of the mold block100 is present. Where the plane having the element X=0 signifies theplane of the mold block 100 placed in Z Y directions. If the partingline which intersects with the plane having the element X=0 has beendetected in step J5 (YES), then in step J6 the parting line is split atan intersecting point with the plane having the element X=0, and thenthe process goes to step J7. Unless the parting line intersecting withthe plane having the element X=0 has been detected in step J5 (NO), thenin step J7 the mold split section 52 may detect position of the elementePL(n) of the parting line.

[0302] If the element X>0 of the mold block 100 has been detected instep J7 (YES), then in step J8 the parting line may be projected ontothe surface of the mold block 100 in the +X direction. Conversely, ifthe element X<0 has been detected in step J7 (NO), then in step J9 themold split section 52 may project the parting line onto the surface ofthe mold block 100 in the −X direction.

[0303] In addition, in step J10, it may be detected whether or not theparting line which intersects with the plane having the element Y=0 ofthe mold block 100 is present. Where the plane having the element Y=0signifies the plane of the mold block 100 placed in the Z·X directions.If the parting line which intersects with the plane having the elementY=0 has been detected in step J10 (YES), then in step J11 the partingline is split at an intersecting point with the plane having the elementY=0, and then the process goes to step J12.

[0304] Unless the parting line intersecting with the plane having theelement Y=0 has been detected in step J10 (NO), then in step J12 themold split section 52 may detect position of the element ePL(n) of theparting line. If the element Y>0 of the mold block 100 has been detectedin step J12 (YES), then in step J13 the parting line may be projectedonto the surface of the mold block 100 in the +Y direction. On thecontrary, if the element Y<0 has been detected in step J12 (NO), then instep J14 the mold split section 52 may project the parting line onto thesurface of the mold block 100 in the −Y direction.

[0305] In step J15, a ruled plane may be formed between the curveprojected onto the mold block 100 and the parting line provided on theproduct shape. In step J16, the curve projected onto the mold block 100and the parting line provided on the product shape are connected to eachother. As a result, four parting planes 200 have been formed in the X·Ydirections.

[0306] In step J17, as shown in FIG. 30B, the parting plane 200 may bedepicted on the display 19. In FIG. 30B, the parting line provided onthe product shape may be projected onto four side surfaces of the moldblock 100. FIG. 30C illustrates offset parting line projected onto fourside surfaces of the mold block 100 in an enlarged manner. In otherwords, coordinates of the edges of the projected parting line areextended to the corners of the mold block. Otherwise, the parting linemay be formed on the edge portions of the mold block by magnifying edgeportions of the product shape with a particular point on the flatsurface including two parting lines as the magnification center and thenprojecting them onto the mold block. In this manner, the parting plane200 for splitting the mold block into the cavity 3 and the core 4 hasbeen formed. In FIG. 30C, a single arrow line signifies the parting lineprovided on the product shape, and a double arrow line signifies theparting line obtained by magnifying the curve projected onto the moldblock 100.

[0307] If the designer has designated the circular cylinder as theprofile of the mold block 100 in step J3, then in step J18 thecoordinate system may be defined wherein the mold opening direction isset as a Z axis and X and Y axes are not particularly specified.

[0308] In step J19, a directional vector for similar magnification ofthe elements of the parting line may be calculated. Where thedirectional vector for similar magnification signifies a line segmentwhich may lie from an origin of the parting line, being to be magnifiedarbitrarily, to a definition point of the parting line.

[0309] The process then advances to step J20 where a Z axis component ofthe foregoing directional vector for similar magnification may be set tok=0. In step J21, the elements of the parting line may be magnified inparallel to the X·Y plane, and then the parting line may be projectedonto the surface of the mold block 100. Here previously modified vectormay be used. In step J22, the mold split section 52 may form a ruledplane between the curve projected onto the surface of the mold block 100and the parting line provided on the product shape 1.

[0310] While, if it has been decided in step J3 that the mold block 100is not the rectangular parallelepiped nor the circular cylinder, then instep J23, as another case, the coordinate system may be defined whereinthe mold opening direction is set as a Z axis and X and Y axes are notparticularly specified. In step J24, the designer may input the plane tobe projected, i.e., the objective projection plane, into the mold splitsection 52.

[0311] Then, in step J25, a projection directional vector may be input.In step J26, the direction of the projection directional vector may beset to the X′ axis. Subsequently, in step J27, it may be detectedwhether the parting line which intersects with the plane having theelement X′=0 of the mold block 100 is present or not.

[0312] If the parting line intersecting with the plane having theelement X′=0 is present in step J27 (YES), then in step J28 the partingline may be split at the point intersecting with the plane having theelement X′=0. Then, the process proceeds step J29. If there has been noparting line which intersects with the plane having the element X′=0 instep J27 (NO), then in step J29 position of the line elements of theparting line may be detected. In case X′>0 in step J29 (YES), then instep J30 the parting line may be projected onto the surface of the moldblock 100 in the +X′ direction. Conversely, in case X′<0 in step J29(NO), then the process goes to step J30.

[0313] Then, in step J31, the ruled plane may be formed between thecurve projected onto the mold block 100 and the parting line provided onthe product shape.

[0314] In step J32, it may be detected whether or not a succeedingprojection direction remains. If the succeeding projection direction hasbeen detected in step J32 (YES), then the process returns to step J24 soas to execute steps J24 to J32 repeatedly. Instead, unless thesucceeding projection direction has been detected in step J32 (NO), thenthe process may be ended.

[0315] With the foregoing processes, the parting plane 200 for splittingthe mold block 100 into the cavity 3 and the core 4 may be formed.Cavity/core split information are stored as cavity/core data D4 into thework memory 13. The cavity may constitute the fixed side of the mold andthe core may constitute the movable side of the mold. The cavity and thecore can be registered as individual parts.

[0316] In this fashion, according to the mold design method of the ninthembodiment of the present invention, it would be apparent that theparting plane 200 may be formed in the mold split section 52 byextending the parting line for splitting the mold block 100 in parallelto the designated direction. Therefore, position coordinates of theparting line may be utilized as the starting point coordinates of theparting plane 200. Accordingly, since the parting plane 200 may beformed by merely designating the position coordinates of the partingline, a burden of the designer can be significantly reduced in contrastto the case where all new coordinates have to be input as the partingplane 200. Besides, man-hour for design can be extremely cut down.

[0317] According to the ninth embodiment of the present invention, itshould be noted that the parting plane 200 may be formed by providing anarbitrary offset amount to the parting line for splitting the mold block100 and then magnifying the parting line in the designated direction.Therefore, only by designating the magnified position of the partingplane 200, the designer can clearly grasp, for example, which plane maysplit the mold block 100 being displayed in three-dimensional fashioninto the core and the cavity.

[0318] According to the ninth embodiment of the present invention, itwould be evident that, since the parting plane 200 for splitting themold block 100 into the core and the cavity may be displayedthree-dimensionally in the perspective view, the convex portion of themold block 100 serving as the core of the mold can be confirmed from theconcave portion side of the mold block 100 serving as the cavity of themold. In this manner, the parting plane 200 passing through the partingline can be formed effectively.

[0319] (10) Tenth Embodiment

[0320]FIGS. 31A to 31C are flowcharts illustrating detection process ofa depth of the mold and split candidate position according to the tenthembodiment of the present invention. In this process, in order tofacilitate fabrication of the cavity 3 and the core 4, the cavity 3 andthe core 4 may be formed as the nest structure depending upon the depthof the mold in the nest split section 502. In order to form the neststructure, nest split candidates must be detected based on the depth ofthe mold.

[0321] In FIG. 31A, in step K1, cavity/core data D4 may first be readfrom the work memory 13. In step K2, the flat surface may be positionedon a location at which the depth of the mold must be inspected. In stepK3, a sectional shape of the mold may be displayed on the display 19 toinspect the depth. Here, as shown in FIG. 32, a neutral plane of themold may be displayed on the display 19. Where the neutral planesignifies a plane formed by collecting thickness central points of themoldings, and it further includes the plane separated from the wallsurface at a constant distance in the concave portion, as shown by adot-dash line in FIG. 32. In FIG. 32, a reference 100A denotes a cavityportion constituting the moldings; 100B, split line candidate portions;100C, deepest portion of the mold; 100D, portion wherein its Z componentbeing suddenly changed on the neutral plane (abruptly changingconcave/convex portion); and 100E, portion corresponding to the rib ofthe moldings, etc. on which the neutral plane must be branched.

[0322] In step K4, the thickness central line may be detected byretrieving (decaying) the cavity 3 (cavity portion). The thicknesscentral line signifies a line which may pass the center in the edgethickness direction of resin of the moldings.

[0323] In step K5, a reference line used for measuring the depth of themoldings may be defined. In step K6, an upper limit value for providinga depth detection range may be input according to the instruction issuedfrom the designer.

[0324] In steep P7, pixels on the thickness central line may be read.Then in step K8, the straight line passing the pixels on the thicknesscentral line and being in parallel to the mold opening direction may beformed. In step K9, an intersecting point of the previous straight lineand the reference line may be calculated.

[0325] In step K10, a distance between pixels on the thickness centralline and the intersecting point may be calculated. Then the distance perone pixel may be calculated in units of mm.

[0326] Then in step K11, the distance previously calculated and an upperlimit value of the depth may be compared with each other. In otherwords, it may be determined whether or not the calculated distance islonger than the upper limit value of the depth. If the distancepreviously calculated has been longer than the upper limit value of thedepth (YES), then the process proceeds to step K12. On the other hand,if the distance previously calculated has been less than the upper limitvalue of the depth (NO), then the process advances to step K15.

[0327] In step K12, edges near the pixel on the thickness central linemay be detected. The edge detection may be done by the screen positionfunction which has already been explained. Edges of the deepest portionof the mold can thus be detected. Line elements extending from theseedges are decided as candidates of the nest split line.

[0328] In step K13, lines extending from the edges of the deepestportion may be registered as candidates of the nest split line. Thisregistration may be done by assigning the nest split line candidate IDand algorithm to the cavity/core data D4. The algorithm would determinedraft order of respective nest structures.

[0329] In step K14, for easy monitoring of the designer, the isometricdrawing of the mold as shown in FIG. 6 may be displayed with differentcolor tone on the display 19. In step K15, it may be checked whether ornot succeeding pixels is present. If there have been succeeding pixels(YES), then the process returns to step K7 where pixels on the thicknesscentral line may be read. Then, succeeding steps P8 to P14 would beeffected repeatedly. With the above processes, candidates of the nestsplit line of the mold can be detected.

[0330] In step K16, the number of pixel near the depth to be detectedmay be input. As the number of pixel, (odd number)2 −1 may be inputdepending on neighboring pixels the depth of which is to be detected.For example, the number of pixel is 3²−1=8, 5²−1=24, or the like.Designation of input pixel may be input by the designer.

[0331] In step K17, adjacent pixels may be detected in the pixel matrixhaving the neighboring pixel number designated by the designer. If theadjacent pixels has been detected (YES), the process goes to step K21.Unless the adjacent pixels has been detected (NO), then in step K18edges near the pixel may be detected. Such edge detection may beeffected by screen position function. In step K19, the edges may beregistered as candidates of the nest split line. Upon registering theedges, nest split line candidate ID and algorithm are assigned to thecavity/core data D4. The algorithm may determine draft order ofrespective nest structures.

[0332] In step K20, for easy monitoring of the designer, the isometricdrawing of the mold may be displayed with different color tone on thedisplay 19. In step K21, it may be checked whether or not succeedingpixel is present. If the succeeding pixel has been present (YES), thenthe process returns to step K17 where pixels on the thickness centralline may be read out. Thereafter, succeeding steps K18 to K20 would berepeated. Thus circumstances around the adjacent pixels can be found atthe candidate positions for splitting the mold in the depth direction.

[0333] In step K22, an upper limit value (absolute value) of gradientrate (rate of change) of the depth may be input. In step K23, pixels atcandidate locations for splitting the depth may be read. In step K24,the number n of pixel may be input to approximately calculate thegradient of the depth. Then in step K25, right and left side gradientsas for the pixel being read out from the work memory 13 may becalculated.

[0334] In step K26, difference between the right and left side gradientsmay be compared with the upper limit value of change rate of thegradient. If the difference between the right and left side gradientshas been greater than the upper limit value of rate of change of thegradient (YES), then in step K27 edges near the pixel may be detected.The edge detection may be executed by screen position function. In stepK28, the edges may be registered as candidates of the nest split line.Upon registering the edges, nest split line candidate ID and algorithmare assigned to the cavity/core data D4. The algorithm may determinedraft order of the nest structures.

[0335] In step K29, for clear monitoring of the designer, the isometricdrawing of the mold may be displayed with different color tone on thedisplay 19. Then the process goes to step K30. On the contrary, if thedifference between the right and left side gradients has been less thanthe upper limit value of change rate of the gradient in step K26 (NO),then in step K30 it may be checked whether or not succeeding pixel ispresent. If the succeeding pixel has been present (YES), then theprocess returns to step K26 where the difference between the right andleft side gradients of the pixel and the upper limit value of changerate of the gradient may be compared with each other. Steps K27 to K29may be performed one more time. While, if there has been no succeedingpixel in step K30 (NO), then the process would be terminated. With theabove processes, the nest split candidates for forming the nestcorresponding to the depth of the mold may be detected.

[0336] As described above, according to the mold design method accordingto the tenth embodiment, it should be noted that, by extending the edgepoint near the deepest position from the split plane of the mold block100 in the split direction of the mold block 100, candidates of thesplit borderline for splitting the core of the mold block 100 into thenest parts may be extracted.

[0337] Therefore, even if the sectional shape of the product 1 viewedfrom the direction being parallel to the split direction of the moldblock 100 is complicate like a comb shape, the optional item can beoffered to the designer which enable the nest profile to be most readilyformed as the mold parts. As a result, even if the mold cavity should beformed as a deep pocket shape which would be of course difficult to beformed, the core 4 may be split into the most suitable nest profile.

[0338] (11) Eleventh Embodiment

[0339]FIG. 33 is a flowchart illustrating assignment process of prioritylevels to nest split line candidates according to the eleventhembodiment of the present invention. In this process, the prioritylevels may be assigned to the parting lines for splitting the cavity 3and the core 4 in the nest split section 502.

[0340] Referring to FIG. 33, in step L1, the cavity/core data D4 inwhich the nest split line candidates has been detected may be read fromthe work memory 13. As shown in FIG. 33, the neutral plane may bedisplayed on the display 19.

[0341] In step L2, with respect to both the portions to which largesurface unevenness of the mold has to be required and the portions inwhich the cavity portion of the mold has to be formed as a deadendportion, the split line candidates may be read. The split linecandidates may be recognized by IDs of the cavity/core data D4 read outfrom the work memory 13.

[0342] In step L3, the split candidate lines may be displayed on theneutral plane on the display 19 according to the split line candidatesderived from IDs of the cavity/core data D4. The split candidate linesare illustrated by the broken line, as shown in FIG. 34. Then linesbeing in parallel to the mold opening direction (Z) and passing thesplit candidate lines are drawn. The parallel lines are illustrated bythe solid lines, as shown in FIG. 34.

[0343] After this, in step L4, the designer may instruct the startingpoints to assign priority levels. Then in step L5, lines beingperpendicular to the mold opening direction and passing the startingpoints are drawn. In step L6, such points may be formed that pass theabove lines being perpendicular to the mold opening direction andpassing the starting points, and pass the split candidate lines (shownby dots in the sectional view), and also intersect with the parallellines in the mold opening direction.

[0344] In step L7, intersecting point numbers may be assigned insequence from the starting point side in respective right and leftdirections. In other words, R1={circle over (1)}, R2={circle over (2)},R3={circle over (3)} . . . are labeled in sequence to the right side,and L1={circle over (1)}, L2={circle over (2)}, L3={circle over (3)} . .. are labeled in sequence to the left side.

[0345] In step L8, it may be determined whether or not the intersectingpoint numbers are either odd number or even number. If the intersectingpoint numbers have been even number (YES), then in step L9 where thecandidate lines may be registered as the candidate with higher prioritylevel. IDs may be assigned split line candidates of the cavity/core dataD4.

[0346] In the next, in step L10, with changing color of the portions tobe selected as the split line candidates, the display may be switchedfrom the neutral plane of the mold to the isometric drawing on thedisplay 19. The process then proceeds to step L11. Alternatively, if theintersecting point numbers have been even number in step L8 (YES), thenin step L11 it may be checked whether or not succeeding intersectingpoint is present. If there is the succeeding intersecting point in stepL11 (YES), the process returns to step L8 where it may be determinedwhether the intersecting point numbers are either odd number or even

[0347] number. Then following steps L9 and L10 would be repeated.

[0348] If there is no succeeding intersecting point in step L11 (YES),then the process may be ended. With the above, priority levels may beassigned to the parting lines for splitting the cavity 3 and core 4.

[0349] In this manner, in the mold design method according to theeleventh embodiment, according to rules caused by the restriction onprocess for the mold parts, priority levels have been assigned to thecandidates of the split borderlines for the nest parts in step L9.Therefore, the designer may design the nest profile to be most readilyformed as the mold parts by selecting the candidates of the splitborderlines of the nest parts in compliance with the priority levelseven if the sectional shape of the mold cavity is complicate like thecomb shape. As a result, the designer having no experience can designeasily the nest structure.

[0350] (12) Twelfth Embodiment

[0351]FIGS. 35A and 35B are flowcharts illustrating arrangement processof the mold base according to the twelfth embodiment of the presentinvention. In this process, the mold base may be arranged for fixing themold, and the mold may be fixed by the plates in the mold base arrangingsection 61.

[0352] Referring to FIG. 35A, in step M1, the cavity/core data D4 mayfirst be read out from the work memory 13. In step M2, the mold basehaving a suitable size in which the cavity and the core can be housedmay be read out. The mold base constitutes the plate for fixing themold. In the twelfth embodiment of the present invention, as for themethod for fixing the cavity and the core to the plate, clamping screwor rib, fixing position, nominal designation of thread or rib dimensionetc. may be patternized. Mold base data D2 obtained by patternizing thefixing parts have been stored in the base file 12.

[0353] In step M3, the mold base arranging section 61 may arrange thecavity and the core in the mold base. In step M4, the profile (moldblock) of the cavity and the core may cut off from the plate of the moldbase. In the mold split section 52, cutting-off of the profiles of thecavity and the core may be effected by the solid/hollow inversionfunction in terms of Boolean operation.

[0354] In step M5, parts of the cavity and the core may be read out. Instep M6, the designer may specify the parts serving as the base.

[0355] In step M7, the designer may select the fixing structure of themold. In the event that the mold should be fixed by the pocket holes andscrews, then in step M8 the depth of the pocket hole may be input. Theconnection diagram between the plate and the block, as shown in FIG. 36,may be displayed on the display 19. In FIG. 36, a reference 101 denotesa plate in which a pocket hole (spot facing hole) 102 is formed, and areference 201 denotes a block in which a tapped hole 104 is formed. Theplate 101 may support the block 201 which holds the nest therein. FIG.36 illustrates the case wherein the plate 101 and the block 201 arefixed by the screw 103.

[0356] In step M9, the pocket hole 102 may be formed in the plate 101.The pocket hole 102 is formed by cutting off the plate 101 serving asthe base to the middle of its thickness. Then the process advances tostep M11 in FIG. 35B.

[0357] In the event that the designer has selected the case the moldshould be fixed by the cut-off holes and screws in step M7, then in stepM10 the cut-off holes may be formed. The cut-off holes may be formed bycutting the base parts off so as to pass through it. Thereafter, in stepM11 in FIG. 35B, clearance (designation) and depth of the fixing screwsare input. In step M12, the number and location of the fixing screws areinput.

[0358] In step M13, tapped holes may be formed in the screw parts to befixed to the plate, and in step M14 spot facing holes for the fixingscrews may be formed. The spot facing holes may be formed in the platelocated beneath the mold. The process then advances to step M19.

[0359] If the designer has not selected the screw clamping by way of thepocket holes or the cut off holes in step M7, then the process goes tostep M15. For example, there is a case where the designer intends to fixthe nest shown in FIG. 37A in the block. In FIG. 37A, a reference 201denotes a block having the pocket holes (spot facing holes) 203 and thetapped holes therein, and a reference 202 denotes a nest having a tappedhole 205 therein. Now FIG. 37A illustrates the case wherein the nest 202may be put into the spot facing hole in the block 201 and fixed by thescrew from the bottom surface.

[0360] In FIG. 37B, a reference 206 signifies a block having a steppedopening portion 207, and a reference 208 signifies a nest having a rib209. FIG. 37B illustrates the case where the nest 208 may be insertedfrom the bottom surface of the block 206 and then fixed by other plate.The rib 209 of the nest 208 cannot be drafted because of its engagementwith the stepped opening portion 207.

[0361] The cut-off holes for the parts being fixed to the plate 101serving as the base may be formed. In step M16, shape and dimension ofthe rib of the nest may be input.

[0362] In step M17, ribs may be provided to the nest, etc. In step M18,clearance (relief) for the rib may be formed in the parts serving as thebase. After this, in step M19, it may be checked whether or notsucceeding parts is present. If the succeeding parts has been present(YES), then the process returns to step M5. There the mold base data maybe read out from the base file 12, and steps M6 to M18 may be repeated.Unless the succeeding parts has been present (NO), then the process maybe completed. With the above processes, the mold may be arranged in themold base.

[0363] As stated earlier, according to the mold design method accordingto the twelfth embodiment, it would be evident that the designer maydesign the fixing parts by selecting in step M7 any of the fixing partsstructures such as clamping screw, rib, etc. those being patternized inadvance, then displaying the fixing parts in the perspective view of themold model, and then inputting fixing location, nominal designation ofthread, rib dimension etc. via the keyboard. Therefore, the designer mayget the fixing parts structures instead of designing them at thebeginning. As a result, a burden of the designer can be extremelyreduced.

[0364] As discussed in the twelfth embodiment, clamping screw, rib, etc.are prepared preliminarily as patternized information of the fixingparts. Thus, it would be evident that, since input items can bedecreased significantly, the fixing structures of the mold parts may bedesigned in a short time and that, even if the designer has littleknowledge concerning the injection molding, he or she may design thefixing structures of the mold parts. As a result, such design operationmay be conducted effectively.

[0365] (13) Thirteenth Embodiment

[0366]FIG. 38 is a view showing an image on the display upon designingthe gate according to the thirteenth embodiment of the presentinvention. FIG. 39 is a flowchart illustrating design process of thegate structure according to the thirteenth embodiment of the presentinvention. In this process, the gate used for injecting the resin intothe mold may be designed in the gate design section 62.

[0367] Referring to FIG. 38, the designer may display a mold design menuscreen on the display 19 to then select “gate design”. In FIG. 39, instep N1, the designer may first select either the mold design oftwo-plate structure or the mold design of three-plate structure. In themold of two-plate structure, the runner stripper plate for introducingthe resin into the cavity has been omitted. The mold of three-platestructure comprises the runner stripper plate, the cavity plate, and thecore plate.

[0368] If the mold of two-plate structure may be selected (YES), then instep N2 the top view of the parting plane for splitting the mold may bedisplayed on the display 19. Then the process goes to step N3 where thedesigner may select kinds (type, dimension) of the gate. If the designerhas selected the side gate in step N3 (YES), then in step N4 thedesigner may instruct the gate location. Now, as shown in FIG. 40, theisometric drawing of the core 4 and the moldings 100 may be depicted onthe display 19. In FIG. 40, a reference 301 is a gate which is providedin the core 4. In step N5, a sectional shape and dimension of the gateare input, and in step N6 a geometric locus of the gate may be formed.The gate forming direction is Y direction, as shown in FIG. 40.

[0369] In the case of designing the side gate, as shown in FIG. 41A, thegate forming direction may be defined by the composite vector in the Xand Y directions. Default (not arranging direction) is +X direction. Alength in the (+) direction and a length in the (−) direction are inputbased on the parting line. It may be selected by the foregoing menuscreen in FIG. 38 whether or not the side gate is provided in either thecavity 3 or the core 4.

[0370] In step N7, the designer may instruct a groove which is to beimpressed on the contacted surface of the cavity and the core. Then agroove may be formed by sweeping the gate profile along the partingplane.

[0371] If the designer has selected a submarine gate in step N3 (NO),then in step N8 the designer may designate a gate location. Then in stepN9, a diameter of the gate and a taper thereof may be input. In stepN10, a slant angle of the gate may be input. In step N11, the designermay instruct a groove which is to be impressed on the contacted surfacebetween the cavity and the core. In the gate design section 62, a groovefor the gate of the circular cone provided on the deepest plane may beformed.

[0372] Conversely, if the designer has designed the mold of three-platestructure in step N1 (YES), then in step N12 the designer may designatea gate location. Instruction of the gate location may be input byselecting the foregoing menu screen in FIG. 42. Then in step N13, adiameter of the gate and a taper thereof are input.

[0373] In step N14, the designer may read a pin gate (gate bush) havinga profile being closet to the gate profile, for example, from the basefile 12. The gate bush is a mold standard parts, wherein bush holeforming location, spot facing diameter, spot facing depth, holediameter, and hole depth are normalized, as shown in FIG. 41B.

[0374] In step N15, the gate bush may be placed on the isometricdrawing, etc of the mold. With the above process, side gate, pin gate,etc. for injecting the resin into the mold may be designed.

[0375] In the mold design method according to the thirteenth embodiment,the designer may display the selected gate on the perspective view ofthe mold model by selecting in steps N1 or N3 one of the side gate,submarine gate, pin gate, etc. all being patternized previously, so thathe or she may design the gate structure such as gate location, type anddimension of the gate, treatment of the connection portion, etc. via thekeyboard 17. Therefore, the designer may get the gate structures withoutdesigning them at the beginning. As a result, the thirteenth embodimententails such an advantage that a burden of the designer can be extremelyreduced. Furthermore, in the thirteenth embodiment, since variousparameters required for providing the gates are patternized, designoperations may be simplified. In other words, since input items can besignificantly decreased because of patternization of the parameters, thedesigner may design the gates in a short time.

[0376] (14) Fourteenth Embodiment

[0377]FIG. 43 is a view illustrating an image on the display at the timewhen the runner may be designed according to the fourteenth embodimentof the present invention. FIG. 44 illustrates a flowchart for designingthe runner according to the fourteenth embodiment of the presentinvention. In this process, a runner for use in introducing the resininto the mold in the lateral direction will be designed in the runnerdesign section 63.

[0378] Referring to FIG. 43, the designer may display mold design menuscreen on the display 19 to select “runner design”. In FIG. 44, in stepO1, the designer may select either mold design of two-plate structure ormold design of three-plate structure. If the designer has selected “molddesign of two-plate structure” (YES), then in step O2 the top view ofthe contacting plane (parting plane) between the cavity and the core maybe displayed on the display 19. Then the process advances to step O4.

[0379] On the contrary, if the designer has selected “mold design ofthree-plate structure” in step O2 (NO), then in step O3 the top view ofthe contacting plane (parting plane) between the cavity plate and therunner stripper plate may be displayed on the display 19. Then in stepO4, a runner locus may be formed on the top view of the mold. AS shownin FIG. 45, the runner may be formed in the Y direction succeedingly tothe gate 301. The runner locus may displayed by a straight line.

[0380] Thereafter, in step O5, the designer may determine a sectionalshape of the runner. The runner locus may be determined when thedesigner designate locations of the cavity and the core on the menuscreen. The runner locus may be designed by employing either a methodfor designating the starting point and the end point and then connectingthem or a method for inputting the starting point and incremental value.The sectional shape of the runner may be designated by the designer onthe menu screen.

[0381]FIGS. 46A to 46D show the sectional shape and the dimension of therunner. FIG. 46A shows the runner having a rectangular sectional shape.For the rectangular runner, a width and a height may be specified on thebasis of the parting line PL. FIG. 46B shows the runner having atrapezoidal sectional shape. For the trapezoidal runner, upper and lowerbase dimensions and a height may be specified on the basis of theparting line PL. FIG. 46C shows the runner having a semicircularsectional shape. For the semicircular runner, a diameter may bespecified on the basis of the parting line PL. FIG. 46D shows the runnerhaving a circular sectional shape. For the circular runner, a diametermay be specified on the basis of the parting line PL.

[0382] If the designer has selected the case the sectional shape of therunner should be formed as a circular one, then in step O6 a radius ofthe circle may be input. If the designer has selected the case thesectional shape of the runner should be formed as an upward semicircularone, then in step O7 a radius of the upward semicircle may be input. Ifthe designer has selected the case the sectional shape of the runnershould be formed as an upward trapezoidal one, then in step O8 therunner design section 63 may input dimensions of the trapezoid. If thedesigner has selected the case the sectional shape of the runner shouldbe formed as a downward trapezoidal one, then in step O9 the runnerdesign section 63 may input dimensions of the trapezoid. If the designerhas selected the case the sectional shape of the runner should be formedas a downward semicircular one, then in step O10 the runner designsection 63 may input a radius of the downward semicircle.

[0383] In step O11, the runner sectional shape may be sweeped along therunner locus to result in a stereoscopic profile of the runner.

[0384] In step O12, the runner design section 63 may attach rotationbodies (½) both having the same sectional shape to edges of the runner.The rotation body signifies a cutting tool for connecting the runner tothe gate. ½ denotes a rate at which the cutting tool abuts a cut plane,i.e., a plane to be cut.

[0385] In step O13, impression may be performed in compliance with thesectional shape of the runner. In the case of the runner having thecircular sectional shape, in step O14 both sides of the contacting planebetween the cavity and the core may be impressed. The impression may bederived from logical difference in the sweeped runner profile. In thecase of the runner having the upward semicircular sectional shape andthe upward trapezoidal sectional shape, in step O15 the upper side ofthe contacting plane may be impressed. The impression may be derivedfrom logical difference in the sweeped runner profile. In the case ofthe runner having the downward semicircular sectional shape and thedownward trapezoidal sectional shape, in step O16 the lower side of thecontacting plane between the cavity and the core may be impressed. Theimpression may be derived from logical difference in the sweeped runnerprofile. With foregoing processes, the runner for introducing the resininto the mold in the lateral direction has been able to be designed.

[0386] In the fashion described above, the mold design method accordingto the fourteenth embodiment, the designer may display the selectedrunner as the perspective view of the mold model on the display 19 byselecting either the two-plate runner structure or the three-platerunner structure, both being preliminarily prepared as patternizedinformation. Then the designer may design the runner structure byselecting runner sectional shape, respective dimensions of runnersectional shape, locus, and process for the connecting portion, andinputting numeral values via the keyboard 17. Therefore, the designermay attain the runner structures without designing them at thebeginning. As a result, the fourteenth embodiment may achieve such anadvantage that a burden of the designer can be extremely reduced.

[0387] According to the fourteenth embodiment of the present invention,it would be understood that, since runner sectional shape of two-plateor three-plate type, respective dimensions of runner sectional shape,locus, etc. are prepared as patternized information, input items by thedesigner can be significantly reduced, and therefore the designer maydesign the runners in a short time. In addition, the designer havinglittle knowledge about the injection molding may also design therunners.

[0388] (15) Fifteenth Embodiment

[0389]FIG. 47 is flowchart illustrating design process of the gas ventaccording to the fifteenth embodiment of the present invention. In thisprocess, the gas vent may be designed in the gas vent design section 65to release the air from the cavity portion of the cavity/core when theresin is poured into the mold.

[0390] In FIG. 47, in step P1, the top view of the parting plane 200including the product shape, as shown in FIG. 48, is displayed on thedisplay 19. In FIG. 48, a reference 303 denotes an ejector pin hole. Theejector pin (not shown) may be passed through the ejector pin hole 303when the moldings 1 is drafted.

[0391] Next, in step P2, final shot position information as the resultof resin superplasticized analysis may be read. The resinsuperplasticized analysis denotes a simulation as for the flowingdirections (weld lines) taken by the resin when it is injected throughthe gate previously designed. According to this analysis, arrival pointsof the resin may be understood as the final shot position.

[0392] In step P3, the final shot position may be displayed on thedisplay 19 so as to be superposed on the top view of the core includingthe product shape shown in FIG. 48. Then, in step P4, it may be detectedwhether or not the resin (weld line) intersects with the parting line.If it has been detected that the resin can be filled in the cavity corenormally (YES), then in step P5 intersecting points between the partingline and the final shot position may be calculated.

[0393] In turn, in step P6, the designer may instruct the direction ofthe gas vent employing the intersecting point as the starting point. Instep P7, the designer may instruct the location to which the gas vent isprovided. The gas vent would be located on or beneath the parting line.

[0394] In step P8, a width of the gas vent may be input, and in step P9the resin to be used may be input. Then, in step P10, the designer maydecide a depth of the gas vent based on the resin material database. Forinstance, the designer may designate a depth and a width of the gasvent. In step P11, a gas vent groove may be formed by sweeping thesectional shape (rectangle). The gas vent 304 as shown in FIG. 60 isdisplayed on the top view of the mold base superposedly on the display19. The gas vent 304 may be provided on the location opposing to thegate 301. In FIG. 49, the drawing in broken line circle may correspondto a sectional view of the gas vent 304 viewed from I-I′ arrow line. Inthe drawing in broken line circle, a reference a shows a depth of thegas vent, and a reference b shows a width of the gas vent.

[0395] Conversely, if it has been detected in step P4 that the resin maynot intersect with the parting line (NO), then the process goes to stepP12. In case, as the result of the resin superplasticized analysis, ithas been found that a void 305 will be caused at the location shown inFIG. 49A because of the air being caught in the resin, the resin may notintersect with the parting line.

[0396] In step P12, it may be decided whether or not there is an ejectorpin hole 303 near the void 305. If it has been decided that the ejectorpin hole 303 is present (YES), then the process proceeds to step P15. Ifit has been decided that there is no ejector pin hole 303 (NO), then theprocess goes to step P14 where the gas vent design section 65 mayarrange the ejector pin hole 303 in the center of the void 305. Then instep P15, the resin to be used may be input.

[0397] Subsequently, in step P16, the designer may select whether or nota dimensional tolerance of the ejector pin hole 303 must be expanded. Ifit has been selected that the dimensional tolerance must be expanded(YES), then in step P17 where the designer may determine a maximum gapfrom the resin material database. The dimensional tolerance will beexplained in the nineteenth embodiment. In step P18, the dimensionaltolerance of the ejector pin hole 303 may be changed to a range between+0 and -maximum gap.

[0398] Here drawings of the ejector pin hole 303 before and aftermagnification, as shown in FIG. 49B, are depicted on the display 19. InFIG. 49B, ±D is a diameter of the ejector pin hole 303. If the gapshould be expanded, φD+0.01 to φD+0.03 would be calculated.

[0399] If the designer has selected in step P16 that, in place ofexpansion of the dimensional tolerance, an air vent dovetail as shown inFIG. 49C must be provided on the periphery of the ejector pin 306 (NO),then in step P19 a depth of the dovetail may be decided based on theresin material database. In step P20, the number of the dovetail may bedetermined. For purposes of example, in FIG. 49C, a depth of thedovetail has been set within 0.02 to 0.04 mm, and the number of thedovetail has been set to be four.

[0400] In step P21, a length of the dovetail may be input. After this,in step P22, the gas vent may be formed by sweeping the sectional shape(semicircle). With these processes, the gas vent 304 may be designedwhich serves to release the air from the space (cavity) portions of thecavity and the core when the resin is forced to be poured into the mold.

[0401] As has been discussed earlier, according to the mold designmethod according to the fifteenth embodiment, it would be understoodthat the gas vent 304 for releasing the gas has been arranged at thelocation where the resin reaches finally in step P3, based on the resultof the resin superplasticized analysis being superposed on theperspective view of the mold. Therefore, the designer may arrange thegas vent 304 at the location suitable for the resin which being pouredinto the cavity portion of the mold block 100 without regard toexperience and perception of the designer. Besides, it would be clearthat, since the final shot position of the resin may be calculated byway of the superplasticized analysis CAE (Computer-Aided Engineering),the designer may design the gas vent structure without knowledge of theinjection molding resin.

[0402] According to the fifteenth embodiment of the present invention,it should be noted that, if the method has been adopted wherein the gasis released by employing the ejector pin 306, correction operations suchas location modification of the ejector pin 306, provision of thedovetail in the ejector pin 306, and dimension modification of theejector pin 306 may be applicable.

[0403] In case, from the result of the resin superplasticized analysis,it has been seen that the resin cannot reach the gas vent 304 so thatthe gas stays in the cavity portion of the mold block 100 to produce thevoid 305, the gas vent design employing the ejector pin 306 may beadopted. Since a tolerable clearance (width, depth, etc.) may bedisplayed on the display 19, the designer may design the gas vent 304 byinputting necessary dimensions via the keyboard 17.

[0404] Therefore, it is of course that the designer may attain therunner structures without designing them at the beginning. As a result,the fourteenth embodiment may achieve such an advantage that a burden ofthe designer can be extremely reduced.

[0405] According to the fifteenth embodiment of the present invention,it would be evident that, if the designer designates shape andspecification of the gas vent 304 prepared previously as patternizedinformation via the keyboard 17, the profile of the designated gas vent304 may be arranged in the mold model. Therefore, the designer mayobtain the gas vent structures without designing the gas vent 304 at thebeginning, and that a burden of the designer can be extremely reduced.In addition, it would be apparent that, since required parameters arepatternized, simplification of operations can be achieved and, sinceinput items input by the designer can be significantly reduced, thedesigner may design the gas vent 304 in a short time.

[0406] (16) Sixteenth Embodiment

[0407]FIGS. 50 and 51 are views for illustrating images of the displaywhen the ejector pin being designed according to the sixteenthembodiment of the present invention. FIG. 52 is a flowchart illustratingdesign process of the ejector pin according to the sixteenth embodimentof the present invention. In this process, the ejector pin may bedesigned in the ejector pin design section 66.

[0408] Referring to FIG. 50, first the designer may select “ejector pindesign” from mold design menu screen displayed on the display 19. Instep Q1, the cavity/core data D4 are read out, and in step Q2 the topview of the core may be displayed on the display 19. In step Q3,position of the ejector pin 306 may be displayed on the display 19.

[0409] In the next, in step Q4, the designer may select a sectionalprofile of the ejector pin 306. If the ejector pin formed of a round pinhas been selected (YES), “hole design for round pin” may be selected onthe menu screen shown in FIG. 51. So a hole for round pin shown in FIG.41C may be formed. The designer may arrange the hole for round pin onthe basis of the bottom surface of the plate. In addition, the designermay designate minimum hole depth, hole diameter, hole diameter+1 (where1 is relief, i.e., clearance) of the hole for round pin. In step Q5, adiameter of the pin may be input, and the process advances to step Q7.

[0410] If the designer has selected a square pin in step Q4 (NO), “holedesign for square pin” may be selected on the menu screen shown in FIG.51. In step Q6, a pin diameter may be input. Here a hole for square pinshown in FIG. 41D may be displayed on the display 19. The designer mayarrange the hole for square pin on the basis of the bottom surface ofthe plate. In addition, the designer may designate minimum hole depth,square hole dimensions (X, Y), square hole dimensions +1 (where 1 isnominal size) of the hole for square pin.

[0411] In step Q7, a length of a slider portion of the ejector pin 306may be input, and then in step Q7 a stroke of the ejector pin 306 may beinput. Next, in step Q9, appropriate ejector pin 306 will be read fromthe base file 12. The ejector pin 306 has been stored in the database asa mold standard parts. In step Q10, the pin design section 66 may inputa clearance of the pin.

[0412] Subsequently, in step Q11, a hole may be formed in thefeed-through parts. As shown in FIG. 53, the ejector pin 306 and theejector pin hole 303 are displayed on the display 19 so as to overlapwith the top view of the product shape.

[0413] The pin holes 303 must be opened in nest of the core 4, movablemold plate (core plate), movable support plate, and upper ejector plate.

[0414] In step Q12, it will be checked whether or not design of theejector pin 306 has been finished. If design of the ejector pin 306 hasnot been finished (NO), the process returns to step Q3 to repeat stepsQ3 to Q11 once more. If design of the ejector pin 306 has been finishedin step Q12 (YES), the process may be completed. With this process, theejector pin be able to be designed.

[0415] In this manner, according to the injection mold design method ofthe sixteenth embodiment, it would be obvious that, by selecting in stepQ4 any of the structure such as sectional shape, dimension, length ofslide portion, etc. of the ejector pin, all being stored as patternizedinformation, the designer may display selected ejector pin on theperspective view of the mold model on the display 19. It would beapparent that, since the designer may design the ejector pin 306 bydesignating location, dimension, shape, etc. and inputting numerals viathe keyboard 17, he or she may obtain the ejector pin structures withoutdesigning the ejector pin structure at the beginning, and that a burdenof the designer can be extremely reduced. Since kinds of the ejector pin306 such as round pin, square pin, straight pin, stepped pin serving asparameters have been prepared as patternized information preliminarily,operation can be simplified. In addition, since the input items can bereduced extremely because of patternized information, the ejector pin306 can be designed in a short time.

[0416] (17) Seventeenth Embodiment

[0417]FIG. 54 is a view showing an image when designing the cooling pathaccording to the seventeenth embodiment of the present invention. FIG.55 is the isometric drawing of the mold when designing the cooling pathaccording to the seventeenth embodiment of the present invention. Inthis process, the cooling path for cooling the mold may be designed inthe temperature adjusting structure designing section 67.

[0418]FIG. 54 shows a menu screen displayed on the display 19. Thedesigner may select “8. cooling path design” from this menu screen. Onthe menu screen, selection item for formation/deletion of the coolingpath, designation item for the cooling path forming plane, input itemfor the hole diameter of the cooling path, input item for configuration(layout) coordinate are displayed. On the display 19, the X Z flat plane(front plane) and Y Z flat plane (side plane) of the cooling pathdesignated by the designer may be two-dimensionally displayed, holediameter of the cooling path may be displayed as numerical values,configuration coordinate of the cooling path may be displayed asnumerical values, and so forth. FIG. 55 shows the cooling paththree-dimensionally in the mold block in which the mold is included. Inthe seventeenth embodiment, two cooling paths are provided in the core4.

[0419] In FIG. 54, the designer may first display the mold design menuscreen on the display 19, and then select “cooling path design”.

[0420] Then, the isometric drawing of the mold consisting of the cavity3 and the core 4 as shown in FIG. 55 may be displayed on the display 19.In FIG. 55, cooling pipes 308 may cool the mold upon forming the resin.

[0421] In the temperature adjusting structure designing section(abbreviated simply as “temperature adjusting section” hereinafter) 67,a flat plane on which the cooling pipes 308 are arranged may bedetermined according to instruction of the designer. The flat plane maybe set as the X Y flat plane during designing the cooling path. Thedesigner may arrange the cooling pipes 308 on the designated position.At this time, the designer may designate hole diameter of the coolingpipes 308. In the seventeenth embodiment of the present invention,plural positions may be designated continuously. If a “cancel” button ofthe menu screen is pushed, then position designation has been completed.

[0422] In this fashion, according to the mold design method of theseventeenth embodiment, it would be obvious that, by selecting eitherstructure of the cooling pipes 308 stored as patternized informationpreliminarily, the designer may display the selected cooling pipes 308on the perspective view of the mold model on the display 19. It shouldbe noted that, since the structure design of the cooling pipes 308 maybe facilitated if the designer inputs numerical values such as holediameter, position, PT screw nominal size via the keyboard 17, thedesigner may obtain the structure of the cooling pipes 308 withoutdesigning the cooling pipe structure at the beginning, and that a burdenof the designer can be extremely reduced. Since required parameters havebeen prepared as patternized information preliminarily, design operationcan be simplified. Furthermore, since the input items can be reducedextremely because of patternized information, the cooling pipe 308 canbe designed in a short time.

[0423] (18) Eighteenth Embodiment

[0424]FIGS. 56A and 56B shows a sectional view of the mold whendesigning a link structure of three-plate type according to theeighteenth embodiment of the present invention. In FIG. 56A, a reference401 denotes a fixing side clamping plate constituting a main body of theinjection mold machine; 5, runner stripper plate in which the runner isprovided; 3A, cavity plate in which the cavity is provided; and 4A, coreplate in which the core is provided. These plate structure may bepatternized in advance.

[0425] First the designer may select the mold opening control structurefrom the menu screen displayed on the display 19. For the mold openingcontrol structure, the link, puller bolt, etc. have been prepared aspatternized information. As shown in FIG. 56A, the display 19 maydisplay the fixing side clamping plate 401, the runner stripper plate 5,the cavity plate 3A, and the core plate 4A. Next, the designer may inputnecessary dimensions such as positions of the plates 5, 3A and 4A, aseparating distance between the plate 5 and the plate 3A, a separatingdistance between the plate 3A and the plate 4A, etc. via the keyboard17.

[0426] Next, in FIG. 56B, it may be checked whether or not interferenceresides between the link (coupling portion) and plates (i.e., whetherthey may contact with each other or not). A reference 402 denotes a linkwhich may couple these three plates. As shown in FIG. 56B, the display19 may display the view in which the fixing side clamping plate 401, therunner stripper plate 5, the cavity plate 3A, and the core plate 4A arestacked and three plates 5, 3A and 4A are coupled by the link.

[0427] The designer may check whether or not clearance is createdbetween the fixing side clamping plate 401 and the link 402. Thisclearance must be checked to confirm whether or not the link 402 and thefixing side clamping plate 401 can be combined with each other withoutmutual engagement when three plates 5, 3A and 4A are clamped to themold. If there has been no clearance between them, warning,interference, etc. would be displayed on the display 19. With watchingthe screen on the display 19, the designer may correct them.

[0428] As discussed earlier, according to the mold design method of theeighteenth embodiment of the present invention, it would be obviousthat, when the designer select any one of structures of the link 402being patternized preliminarily and stored in the storing means, thedisplay 19 may display the selected link 402 on the perspective view ofthe mold model. Also, by inputting the separating distances betweenrespective plates 5, 3A and 4A via the keyboard 17, the designer maycheck whether or not clearance has been created between the fixing sideclamping plate 401 and the link 402.

[0429] Accordingly, it would be evident that, since the designer mayeffect structure design of the link structure 402 merely by inputtingseparating distances required for mold opening in the injection moldingmachine, he or she may obtain the link structures without designing thelink structure at the beginning, and that a burden of the designer canbe extremely reduced. The designer may design the link structures unlesshe or she knows mold opening operation as to three-plate type structurewell. It would also be evident that, since the mold opening structurehave been prepared as patternized information preliminarily, the inputitems can be reduced extremely, and that the three-plate type link canbe designed in a short time.

[0430] (19) Nineteenth Embodiment

[0431]FIG. 57 is a view showing dimensions of parts having dimensionaltolerance according to the nineteenth embodiment of the presentinvention. In the nineteenth embodiment of the present invention, if thedimensional tolerances have already been decided between parts of themold model, as shown in FIG. 57, half tolerance of the dimension ofgiven parts may automatically modified to central tolerance. By way ofexample, as shown in {circle over (1)} of FIG. 57, the display 19 maydisplay a dimension 50 as a width of the parts, and also display anupper limit +0 and a lower limit −0.2 like “50+2−0.2” as half tolerancetherefor. As for a height of the parts, it may display an upper limit+0.1 and a lower limit −0 like “5+0.1−0” as half tolerance for a heightof 5. The product shape is displayed by central values.

[0432] In the nineteenth embodiment of the present invention, as shownin {circle over (2)} of FIG. 57, the designer may switch the displayinto central tolerance via the keyboard 17. In this event, as shown inFIG. 57, the display 19 may change the width 50, upper limit +0, andlower limit −0.2 of the parts into 49.9±0.1. With regard to the partshaving the height 5, upper limit +0.1 and lower limit −0, the displaymay be changed into 5.05±0.05. Now a dimension ε may be displayed asα±δ. A central value ε is ε=α+[(β+γ)/2], and an error δ is δ=[(β−γ)/2]and δ>0. The half tolerance is also referred to as modificationdirection tolerance.

[0433] Besides, in the nineteenth embodiment of the present invention,as shown in {circle over (3)} of FIG. 57, the screen on the display maybe changed to designer's objective dimension (working target dimension)by varying the central tolerance of the dimension of the parts into thehalf tolerance. The width of the parts of 49.9±0.1 may be modified to49.95. The height of the parts of 5.05±0.05 may also be modified to5.075. Thus, as shown in FIG. 57, correct allowance may be provided inthe directions A and B. Where the working target dimension η may bedisplayed like η=ε+δ·κ. κ is a parameter for the target dimension. Inthe nineteenth embodiment, κ=+½ may be applied.

[0434] If the dimensional tolerance has been fixed between the parts ofthe mold model, the designer may select either the central tolerance orthe half tolerance for the dimensions of the given parts. Thus, based onthe central tolerance or the half tolerance, the display 19 may displaymodified dimensional tolerance between the parts of the mold model.

[0435] As mentioned above, in the mold design method of the nineteenthembodiment of the present invention, if the mold dimensions and theparts dimensions have been given in terms of the half tolerance, thedisplay 19 may display the central tolerance being modified from thehalf tolerance in accordance with instruction of the designer.Therefore, the designer can confirm target working dimensions of theintended mold or the intended parts on the screen.

[0436] Further, in the mold design method of the nineteenth embodimentof the present invention, even if the mold dimensions and the partsdimensions have been given by means of the central tolerance, thedisplay 19 may display the half tolerance being modified from thecentral tolerance in accordance with instruction of the designer.Therefore, the designer can change target working dimensions of intendedmold or parts on the screen. As a result, the dimensions may be modifiedin the direction to which correct allowance has been permitted andwithin limit tolerance.

[0437] According to the nineteenth embodiment of the present invention,in the event that the designer has selected either the central toleranceor the half tolerance for the dimensions of the given parts via thekeyboard 17, the display 19 may display modified dimensional tolerancebetween the parts of the mold model based on the central tolerance orthe half tolerance. Therefore, it would be apparent that the designercan edit target working dimensions of intended mold or parts on thescreen. Thus, artificial error due to missing of the dimensionaltolerance, etc. can be eliminated. The mold can be designed withconsidering the dimensional tolerance.

[0438] In the first to nineteenth embodiments of the present invention,although the methods for designing the mold by reading individual datahave been explained, another method for designing the mold by readingdata groups to which attributes (names) are assigned respectively willbe explained in the twenty-seventh embodiment.

[0439] (20) Twentieth Embodiment

[0440] FIGS. 58 to 60 are views illustrating a design item system of themold design system according to the twentieth embodiment of the presentinvention. In the twentieth embodiment, mold design items are registeredpreliminarily in the design system to effect the mold design readily andquickly.

[0441] In FIG. 58, a reference 22 denotes mold design items. The molddesign items 22 are stored in the other memory 21 and are classifiedroughly into three groups. A reference 23 denotes product shapecorrection items. The correction items 23 are registered contents ofpreliminary between the mold designer and the mold designer to beconducted at the time when the construction of the mold is started. Thecontents of correction items are, for example, determination of moldopening direction, provision of draft slope to the product, detection ofundercut, definition of the parting line, design of the gate, and filemanagement.

[0442] The following will be the design items. The mold openingdirection may be decided to “Z direction” in which the product isreleased from the core. The draft slope may be provided to facilitaterelease of the product from the core. Since the undercut preventsreleasability of the product, the core must be formed as the neststructure. The parting line is formed to obtain the parting plane forsplitting the mold block into the cavity and the core. The gate isprovided to inject the resin into the cavity portion between the cavityand the core. Product shape correction data being derived by correctingthe product shape in compliance with the product shape correction items23 are stored in the work memory 13 and then managed.

[0443] In FIG. 59A, a reference 24 denotes mold design items. The molddesign items 24 for the mold designer's exclusive use are, for example,correction of molding shrinkage rate, formation of cavity/core block,determination of mold base, formation of the parting plane, design ofgate, runner, and sprue, design of mold temperature adjusting waterpath, design of ejector pin, check of hole interference, split of neststructure, design of slide core, and file management.

[0444] The design contents are as follows. In order to improvereleasability of the product, the cavity and the core of the mold may bedesigned by modifying the dimensions according to shrinkage rate of theproduct. The cavity and the core may be designed by splitting the moldblock by means of the parting plane. The mold base may be designed byselecting plates, to which the cavity and the core being fixed, andtheir fixing parts. The parting plane may be designed by selecting theparting line. The gate, runner, and sprue, these constituting resinflowing route, may be designed by selecting respective sectional shapesaccording to viscosity of the resin. The mold temperature adjustingwater path (cooling water path) may be designed by considering otherhole profiles.

[0445] The ejector pin may be designed by checking interference with themold temperature adjusting water path. The undercut portion of theproduct may be formed by splitting the core into nests. The nest partsmay be designed slidably in the X direction or Y direction.

[0446] In FIG. 59B, a reference 25 denotes manufacturing model formingitems. The forming items are incorporated for use in the mold designerand the mold manufacturer. The contents of the forming items areelectric discharge machining electrode design, file management, and thelike. The electric discharge machining electrodes are manufacturing jigsfor machining the inner surface of the cavity. In order to round theedge of the moldings, the inner edge of the cavity may be worked to formthe circular cylinder surface by the manufacturing jigs. Working data(NC data) used to fabricate the electrodes may be stored in the workmemory 13 and then managed. Note that these design items may be storedin the memory 21 shown in FIG. 2. On starting the design system, thesedesign items may be displayed on the display 19 shown in FIG. 2.

[0447]FIG. 60 illustrates classification of the design items in the molddesign system. In FIG. 60, the product designer may design the productshape to be molded by the injection mold. In compliance with the productshape correction items 23 of the mold design system, the productdesigner may effect determination of the mold opening direction,provision of the draft slope to the product, detection of the undercutportion, definition of the parting line, design of the gate, and filemanagement. The product designer may offer the product shape correctiondata to the mold designer. Note that the product shape correctionoperation may be executed by the mold designer.

[0448] In turn, according to the mold design items 24, the mold designermay effect, for example, correction of molding shrinkage rate, formationof cavity/core block, determination of mold base, formation of theparting plane, design of gate, runner and sprue, design of moldtemperature adjusting water path, design of ejector pin, check of holeinterference, split of nest structure, design of slide core, and filemanagement. The mold designer may offer the mold parts data to the moldmanufacturer. Then, according to the manufacturing model forming items25, the mold manufacturer may execute electric discharge machiningelectrode design, file management, etc. It should be noted thatmanufacturing model formation may be done by the mold designer.

[0449] As described above, according to the design item system of themold design system according to the twentieth embodiment of the presentinvention, the design items of the mold have been roughly classifiedinto three categories, i.e., product shape correction items, mold designitems, and manufacturing model formation items, and then registered inthe system.

[0450] Therefore, determination of the mold opening direction, provisionof the draft slope, detection of the undercut portion, definition of theparting line, gate design, etc. may be effected in compliance with theproduct shape correction items, i.e., the contents of preliminarybetween the product designer and the mold designer conducted whenstarting construction of the mold.

[0451] Furthermore, correction of molding shrinkage rate, formation ofcavity/core block, determination of mold base, formation of the partingplane, design of gate, runner and sprue, design of mold temperatureadjusting water path, design of ejector pin, check of hole interference,split of nest structure, design of slide core, etc. may be effected incompliance with the mold design items being incorporated for use in themold designer only.

[0452] Moreover, design of the electric discharge electrodes may beeffected in compliance with the manufacturing model formation itemsbeing incorporated for use in the mold designer and the moldmanufacturer. In that case, since software resources of the system canbe commonly used by the product designer, the mold designer, and themold manufacturer, design of the mold can be done easily and quickly.Preliminary and transfer of the product shape data can be effectedsmoothly when designing the mold, and processes required for thedesigners from the product design to the mold design can be reduced. Adesign method of the manufacturing jigs of the mold parts will beexplained in the twenty-ninth embodiment.

[0453] (21) Twenty-First Embodiment

[0454]FIG. 61 is a flowchart illustrating detection process of theundercut portion of the product according to the twenty-first embodimentof the present invention. FIGS. 62A to 62C, 63A and 63B are viewsillustrating supplementary explanations. In the twenty-first embodiment,as shown in FIG. 62A, detection of the undercut portion of the productshape 26 having two eaves shapes will be explained. In FIG. 62A, areference 26A denotes a first eaves shape which extends from one side ofthe product shape 26 laterally, and a reference 26B denotes a secondeaves shape which is formed beneath the first eaves shape 26A. It may bedetected whether or not the portion existing between two eaves shapes26A and 26B functions as the undercut portion 26C.

[0455] In FIG. 61, in step R1, the designer may first select one ofplanes constituting the product shape 26. For example, an upper plane ofthe eaves profile 26A as shown in FIG. 62B may be selected. In FIG. 62B,the display 19 may display a lattice-like image of the selected plane onthe screen.

[0456] In step R2, the parting line forming section 41 may form dotlines on the upper surface of the eaves shape 26A. It is preferable thatplural dot lines are prepared. For instance, the dot lines may be formedon the intersecting points of the lattice. In the sectional view of theproduct shape 26 in FIG. 62C, a X mark is the location of the dot linesand, for purposes of simplicity in the explanation, only one point isillustrated. Then, in step R3, the parting line forming section 41 mayproject the dot lines on the plane of the eaves profile 26A in the +Zdirection. In FIG. 62C, a black round mark is the projected location inthe +Z direction.

[0457] In step R4, the parting line forming section 41 may detectwhether one or more dot lines can be projected onto other planes or not.In the example in FIG. 62C, dots are projected onto respective edges ofupper and lower portions of the eaves profile 26B (two-pointprojection). If no dot line can be projected on other planes in step R4(NO), then the process proceeds to step R8. On the contrary, if one ormore dot lines can be projected onto other planes in step R4 (YES), thenthe process advances to step R5.

[0458] In step R5, the parting line forming section 41 may project thedot lines on the plane of the eaves profile 26A in the −Z direction. Inthe example in FIG. 62C, a white round mark is the projected location inthe −Z direction. In step R6, the parting line forming section 41 maydetect whether one or more dot lines can be projected onto other planesor not. In the example in FIG. 62C, dots are projected onto an edge ofthe lower portion of the eaves profile 26A (one-point projection).

[0459] If no dot line can be projected on other planes in step R6 (NO),then the process proceeds to step R8. Conversely, if one or more dotlines can be projected onto other planes in step R6 (YES), then theprocess advances to step R7.

[0460] In step R7, the plane may be stored as the plane constituting theundercut portion 26C in the work memory 13.

[0461] In step R8, the designer may decide whether or not detection ofthe undercut has been completed with respect to all planes. Unlessdetection of the undercut has been completed in step R8 (NO), theprocess returns to step R1 where one plane may be selected.Subsequently, steps P2 to P8 are repeated once again.

[0462] By way of example, the upper plane of the eaves profile 26B asshown in FIG. 63A has been selected in step R1. In FIG. 63A, the display19 has displayed the lattice-like image of the selected plane on thescreen.

[0463] In step R2, the parting line forming section 41 may form dotlines on the upper surface of the eaves shape 26B. In FIG. 63B, a × markis the location of the dot lines and, for purposes of clarification ofthe explanation, only one point is illustrated. In this example, thereis shown the case wherein dots are projected onto e lower edge of theeaves profile 26B and upper and lower edges of the eaves profile 26A(three-point projection).

[0464] Then, in step R3, the parting line forming section 41 may projectthe dot lines on the plane of the eaves profile 26B in the +Z direction.In step R4, the parting line forming section 41 may detect whether oneor more dot lines can be projected onto other planes or not. In theexample in FIG. 63A, since there is no projection plane, dots on theplane of the eaves profile 26B cannot be projected in the +Z direction(zero-point projection). If no dot line can be projected on other planesin step R4 (NO), then the process proceeds to step R8.

[0465] If detection of the undercut has been completed with respect toall planes in step R8 (YES), then the process advances to step R9 whereconstituting plane of the undercut portion may highlighted on the screenof the display 19.

[0466] According to the method for detecting the undercut portion of theproduct shape according to the twenty-first embodiment of the presentinvention, it would be obvious that, by forming dot lines on theconstituting plane of the product and detecting whether or not these dotlines can be projected onto other plane located in the ±Z direction, theundercut portion can be detected easily and in a short time in contrastto the seventh embodiment of the present invention.

[0467] (22) Twenty-Second Embodiment

[0468]FIG. 64 is a flowchart illustrating extraction process of theparting line according to the twenty-second embodiment of the presentinvention. FIGS. 65A, 65B and 66A to 66D are views illustratingsupplementary explanations. In the twenty-second embodiment, anextracting function of the parting line is simplfied rather than thefirst embodiment.

[0469] In FIG. 64, in step S1, the designer may first display a profileof the product shape 27 along the +Z direction on the screen of thedisplay 19. FIG. 65A is a perspective view showing the product shape 27of the plastics, and FIG. 65B is a view showing the product shape 27viewed from the mold opening direction (+Z direction). Incidentally,since rear edges of the product shape 27 are obstructive to extractionof the parting line, profile data concerning the rear edges have beenunloaded in the memory.

[0470] In step S2, the parting line forming section 41 may resolvevisible edges of the product shape 27 and the profile lines (edges) intoelements. In the example in FIG. 65B, an outermost peripheral profileline and edges of the product shape 27 are resolved into straight line,circular arc, etc. (referred to as “line element” hereinafter).

[0471] Next, in step S3, the parting line forming section 41 may detecta line element having maximum value in the horizontal direction (Xdirection) of the display screen according to instruction of thedesigner. This is because extraction candidates of the parting linesmust be narrowed to some extent by retrieving the line elements roughly.Detected line elements may be stored in the work memory 13. In step S4,the parting line forming section 41 may detect other line elements beingadjacent to the line elements having the maximum value in the Xdirection. At this time, the display 19 may display the perspective viewof the product shape 27, as shown in FIG. 66A. Then, profile datarelating to rear edges may be read out from the work memory 13, and theparting line is displayed superposedly on the perspective view of theproduct shape 27. Other line elements being adjacent to the lineelements having the maximum value in the X direction may be stored inthe work memory 13 as the candidates of the parting line.

[0472] In step S5, depending upon the cases wherein there is no otherline element adjacent to the line element and wherein two line elementsor more are present as shown in FIG. 66C, the designer may provideinstruction to the system via the keyboard 17. According to the contentsof instruction, in case there has been no other line element adjacent tothe line element, the process goes to step S6 where the line elementsare formed manually. Alternatively, in case there have been two lineelements (1), (2) being adjacent to the line element as shown in FIG.66C, then the process advances to step S7 where the designer may selecteither line element (1) or line element (2) manually. As shown in FIG.66B, in case there has been one other line element being adjacent to theline element, the process proceeds to step S8.

[0473] In step S8, the system may store other line element beingadjacent to the line element in the work memory 13 as the candidates ofthe parting line. In step S9, it may be detected whether or not the lineelements having the maximum value in the X direction have been detectedas adjacent curves, i.e., the line elements have formed a closed loop.

[0474] Unless the line elements have formed the closed loop in step S9(NO), the process returns to step S5. Until the line elements can formthe closed loop, then steps S5 to S8 are repeated.

[0475] If the line elements have formed the closed loop in step S9, thatis, the line elements having the maximum value in the X direction havebeen detected as adjacent curves (YES), the process goes to step S10where the line elements may be extracted as the parting line. In FIG.66C, the parting line of the product shape 27 is shown by the solidline.

[0476] According to the extraction method of the parting line of thetwenty-second embodiment of the present invention, by retrieving theline elements having the maximum value in the X direction of the productshape viewed from the mold opening direction in step S3, extractioncandidates of the parting line have been selected to some extent.

[0477] Therefore, it would be evident that the parting line can beextracted in a short time rather than the first embodiment and that inaddition the parting line can be extracted in an extremely short time incomparison with the conventional case wherein the parting lines areextracted from the two-dimensional drawing.

[0478] (23) Twenty-Third Embodimnet

[0479]FIGS. 67A and 67B are flowcharts illustrating formation process ofthe parting plane according to the twenty-third embodiment of thepresent invention. FIGS. 68A to 68E are views for use in supplementaryexplanations. Unlike the ninth embodiment, in the the twenty-thirdembodiment, a falt surface, a circular cylinder surface, a circular conesurface, and a free-form surface may be extracted correspondingly towhether or not the parting line is on the same flat surface, and thenthe parting plane can be formed by connecting these surfaces mutually.Note that the mold split section 52 may also have this function.

[0480] In FIG. 67A, in step T1, the system may first two adjacentparting lines i, j from n (n=1, 2, 3, . . . i, j, k . . . n) partinglines according to instruction of the designer. In the presentembodiment, it is regarded that, when both the parting line surroundingan outside of a certain region and the parting line surrounding aninside of the certain region can exist, the region may constitute theflat surface.

[0481] In step T2, it is detected whether or not two adjacent partinglines i, j are on the same flat surface. The detection condition is atthis time whether or not two end points constituting a starting pointand an end point of the two parting lines i, j and one connecting pointare on the same flat surface. If two parting lines i, j are on the sameflat surface, e.g., the flat surface N as shown in FIG. 68B (YES), thenthe process goes to step T3. In step T3, it may be detected whether ornot the parting line k adjacent to the parting line j is on the sameflat surface. If two parting lines j, k are on the same flat surface N(YES), then the process proceeds to step T8. Unless two parting lines j,k are on the same flat surface N (NO), then the process proceeds to stepT4 where two parting lines j, k are stored as elements of the flatsurface N.

[0482] Conversely, unless two parting lines i, j are on the same flatsurface in step T2 (NO), then the process goes to step T5 where theparting line i is stored as an unconfirmed element. In the example inFIG. 68B, the parting line adjacent to the flat surface N of the productshape 28 is the unconfirmed element. Thereafter, this will be stored asthe line element of the flat surface N+2.

[0483] In step T6, it may be detected whether or not the parting line kadjacent to the parting line j is on the same flat surface. If twoparting lines j, k are on the same flat surface N in step T6 (YES), thenthe process proceeds to step T8. Unless two parting lines j, k are onthe same flat surface N (NO), then the process proceeds to step T4 wheretwo parting lines j, k are stored as elements of the flat surface N+1.

[0484] In step T8, it may be detected whether or not the last partingline n and the first parting line 1 are on the same flat surface. If thelast parting line n and the first parting line 1 have not been on thesame flat surface (NO), then the process returns to step T1. Twoadjacent parting lines i, j may be selected, thereafter steps T2 to T8are repeated. If the last parting line n and the first parting line 1have been on the same flat surface in step T8 (NO), then the processadvances to step T9. Where it may be decided whether or not all flatsurfaces including the parting line have been detected. If entire flatsurfaces have been detected (YES), then the process advances to stepT10. Unless entire flat surfaces have been detected (NO), then theprocess returns to step T1. Two adjacent parting lines i, j may beselected, then steps T2 to T8 are repeated. As a result, all flatsurfaces including the parting line have been detected.

[0485] In step T10, the designer may detect line elements adjacent tothe flat surface N+1 of the product from unconfirmed elements whilewatching the product shape. This detection of the line elements would bedone to confirm presence of the flat surface adjacent to the flatsurface N+1. In case all flat surfaces have been detected in steps T2 toT8, the line element being adjacent to the flat surface N+1 is any ofcircular cylinder surface, circular cone surface and free-form surface.

[0486] In step T11, the designer may first detect the circular cylindersurface and the circular cone surface from remaining unconfirmedelements. The circular cylinder surface and the circular cone surfacecan be found in the corner portions where inner surfaces of the productshape 28 intersect with each other. In step T12, other unconfirmedelements may as regarded as elements of sweep surfaces (free-formsurfaces). In FIG. 68C, a reference 28A denotes a sweep surface of theproduct shape 28. This surface is a portion where the profile of thecore must be finished to the sweep surface.

[0487] In step T13, a borderline on which two adjacent surfacesintersect with each other (referred to as “intersecting line”hereinafter) may be detected. In the example in FIG. 68D, theintersecting line of the product shape 28 can be found on the portionwhere the flat surface N and the flat surface N+1 intersect with eachother. If the intersecting line can be detected, interference betweenthe flat surfaces can be prevented.

[0488] Subsequently, in step T14, the surfaces may be connected and thentrimmed. In the example in FIG. 68D, the flat surface N and the flatsurface N+2 are connected. In addition, the flat surface N+2 and thecircular cylinder surface are connected.

[0489] In step T15, trimmed surface has been determined as the partingplane of the product shape 28. FIG. 68E shows the parting plane of theproduct shape 28. In FIG. 68E, the parting plane of the product shape 28can be formed by connecting flat surfaces N, N+1, N+4, flat surfacesN+2, N+3 modified by the circular cylinder surface, and the sweepsurface N+5. If the parting plane has been determined, the mold block 29may be split by this parting plane, like the ninth embodiment.Consequently, the cavity block and the core block may be designed.

[0490] As discussed above, according to forming method of the partingplane according to the twenty-third embodiment of the present invention,a falt surface, a circular cylinder surface, a circular cone surface,and a free-form surface may be extracted by detecting whether or not theparting line is on the same flat surface, and then the parting plane canbe formed by connecting these surfaces mutually.

[0491] Therefore, the parting plane of the product shape 28 can beformed readily without projecting the main parting line onto the moldblock after the main parting line being extended in the X, Y directionslike the ninthe embodiment.

[0492] (24) Twenty-Fourth Embodiment

[0493] FIG. 69 is a flowchart illustrating design process of the ejectorpin according to the twenty-fourth embodiment of the present invention.FIGS. 70A to 70D are views for use in supplementary explanations. Unlikethe above sixteenth embodiment, in the twenty-fourth embodiment, theejector pin design section may calculate a height of the ejector pinwhen the designer designates the location of the ejector pin.

[0494] In FIG. 69, in step U1, the designer may first input designdimensions of the ejector pin. Such design dimensions of the ejector pinare input into the design system via the keyboard 17. At that time, amenu screen as shown in FIG. 70A appears on the display 19. Unlike theimage view being explained in the sixteenth embodiment, the hole profileof the ejector pin and instruction boxes in which dimensional values areinput are displayed in this one menu screen. The designer may inputrespective dimensional values into the instruction boxes. Thedimensional values are ejector pin hole diameter, relief hole diameter,guide length, rib diameter, and so on. The rib serves as adisengage-preventing jig which is provided on the lower end of theejector pin.

[0495] In step U2, the display 19 may display the profile of the coreblock viewed along the +Z direction in accordance with instruction ofthe designer. In step U3, the designer may designate the location of theejector pin on the screen of the display 19. In the example in FIG. 70B,a black round mark on the core block 30 means the pin hole. The ejectorpin design section 66 may then detect the pin location coordinates X, Y.The pin location coordinates X, Y are defined by distances from thecenter of the mold.

[0496] The display 19 may display the pin location coordinates X, Y inthe instruction window. It is of course that the designer may correctthese values via the keyboard 17.

[0497] Thereafter, in step U4, the ejector pin design section 66 maythen form a circle with the pin designated location as the center. Instep U5, the circle may be projected onto the mold parts. The mold partsare, for example, core block 30, core plate (not shown), support plate,upper ejector plate, and the like. There an assumption is needed thatdesign of the mold base has been completed at this time.

[0498] In step U6, the ejector pin design section 66 may then detect aminimum height and a maximum height of the ejector pin. The height ofthe pin is different according to the surface profile of the product.For purposes of example, if the surface of the product is slant, the topend of the ejector pin must be worked to be slant, so that the ejectorpin has the minimum height and the maximum height. In FIG. 70C, a blackround mark is the maximum height of the ejector pin, while a black star(asterisk) mark is the minimum height of the ejector pin.

[0499] In step U7, the ejector pin design section 66 may set the minimumheight of the ejector pin as the basis of guide length calculation. Theguide length may provide a shift distance (ejection stroke) when themoldings is ejected. The maximum height of the ejector pin is a distancefrom the surface of the lower ejector plate to the top end of theejector pin. The minimum height of the ejector pin is varied incompliance with slant of the product surface. The ejector pin designsection 66 may read dimension values of thicknesses of, for instance,core block 30, core plate (not shown), support plate, upper ejectorplate, etc. from the work memory 13, an then add these thicknesses. Themaximum height of the ejector pin may be derived from the result of thisaddition.

[0500] In step U8, the ejector pin design section 66 may form profilesof the ejector pin and the hole based on ejector pin hole diameter,relief hole diameter, guide length, rib diameter, and so forthdesignated by the designer.

[0501] In step U9, the designer may decided whether or not all ejectorpins have been designed. If all ejector pins have been designed (YES),then the process advances to step U10. Unless all ejector pins have beendesigned (NO), then the process returns to step U1 where dimensionsrequired for design are input. Then, following steps U2 to U9 areexecuted once again.

[0502] In step U10, the designer may determine whether or not designinformation of the ejector pin must be output. If design information ofthe ejector pin must be output (YES), then the process goes to step U11where design information is either displayed on the screen of thedisplay 19 or output on the paper by the printer 20. By way of example,in FIG. 70D, the example has been given wherein the result of design oftwo ejector pins are output on the paper. The output contents are suchas locations, hole diameters, relief hole diameters, guide lengths andejector pin lengths. In step U11, design of the ejector pin may be endedafter design information are output. Unless design information of theejector pin must be output in step U10 (NO), design of the ejector pinmay also be ended.

[0503] As has stated above, according to the design process of theejector pin according to the twenty-fourth embodiment of the presentinvention, when the designer designates the location of the ejector pinon the screen of the display 19, the ejector pin design section 66 maydetect locations X, Y of the ejector pin from the center of the mold,and calculate the height from the upper ejector plate. Thus, it would beunderstood that, although the mold has a complicate profile, the ejectorpin may be designed in an interactive manner between the designer andthe system.

[0504] (25) Twenty-Fifth Embodiment

[0505]FIG. 71 is a flowchart illustrating design process of mold base ofthe mold according to the twenty-fifth embodiment of the presentinvention. FIG. 72 is a view for use in supplementary explanations. Inthe twenty-fifth embodiment, entire profile of the mold baseconstituting the mold, and an instruction boxes in which dimensionalvalues of respective constituent parts are input may be displayed in onescreen.

[0506] In FIG. 71, in step V1, the designer may select kinds of the moldbase of the mold. At this time, the display 19 may display a menuscreen, as shown in FIG. 72. The display contents are mold baseformation, arrangement determination, dimension corection, mold basesave, mold base read, etc. If the designer selects “mold baseformation”, the display 19 may switch to the menu screen showing kindsof the mold base. The kinds of the mold base are SA type, SC type oftwo-plate structure, and DA type, DC type of three-plate structure. SAtype and SC type are the mold consisting of two-mold plates of thecavity plate and the core plate. DA type and DC type are the moldconsisting of three-mold plates of the cavity plate, the core plate andthe runner stripper plate. The SA type and DA type have the supportplate, but the SC type and DA type have not the support plate.

[0507] In step V2, the display 19 may display the instruction window inwhich profile of the mold base and dimensional values are input. In theexample in FIG. 73, entire profile of the SA type mold base andinstruction boxes X, Y, TW, CP, A, B, U, C, SP, EP, E1, and E2, in whichdimensional values of respective constituent parts being input, on onescreen of the display 19. In the example in FIG. 73, a reference {circleover (1)} denotes a fixing side clamping plate; {circle over (2)},fixing side mold plate; {circle over (3)}, movable side mold plate;{circle over (4)}, support plate; {circle over (5)} and {circle over(6)}, spacer blocks; {circle over (7)}, upper ejector plate; {circleover (8)}, lower ejector plate; and {circle over (9)}, movable sideclamping plate.

[0508] X is a lateral length of the fixing side mold plate {circle over(2)}, the movable side mold plate {circle over (3)}, and the supportplate {circle over (4)}. Y is a vertical length of the fixing sideclamping plate {circle over (1)}. TW is a lateral length of the fixingside clamping plate {circle over (1)}. CP is a height of the fixing sideclamping plate {circle over (1)}. A is a height of the fixing side moldplate {circle over (2)}. B is a height of the movable side mold plate{circle over (3)}. U is a height of the support plate {circle over (4)}.C is a height of the spacer blocks {circle over (5)} and {circle over(6)}. SP is a lateral length of the spacer blocks {circle over (5)} and{circle over (6)}.

[0509] EP is a lateral length of the upper ejector plate {circle over(7)} and the lower ejector plate {circle over (8)}. E1 is a height ofthe upper ejector plate {circle over (7)}. E2 is a height of the lowerejector plate {circle over (8)}. A distance between E1 and E2 is 4 mm.

[0510] The designer may input dimentional values into these instructionboxes X, Y, TW, CP, A, B, U, C, SP, EP, E1, and E2 via the keyboard 17.

[0511] In step V3, the mold base forming section 61 may form mold basedata in compliance with dimensional values input by the designer. Theexplanation of the method for forming the mold base data will be omittedsince it has been described in the twelfth embodiment.

[0512] As mentioned earlier, according to the twenty-fifth embodiment ofthe present invention, entire profile of the mold base constituting themold, and instruction boxes in which dimensional values of respectiveconstituent parts are input may be displayed in one screen. Therefore,it would be understood that, with confirming an expected complete shape,the designer may design the injection mold by inputting dimentionalvalues into these instruction boxes X, Y, TW, CP, A, B, U, C, SP, EP,E1, and E2, which thus facilitates the design of the mold.

[0513] (26) Twenty-Sixth Embodiment

[0514]FIG. 74 is a flowchart illustrating usage of the configurationfile of the mold design system according to the twenty-sixth embodimentof the present invention. FIG. 75 is a view for use in supplementaryexplanations. In the twenty-sixth embodiment, usages of the tools forsupporting the mold design system may be disclosed. In FIG. 74, in stepW1, the designer may save the default value file in the system. Thisfile in which the tools for supporting the mold design system arewritten would be written into the memory 21 shown in FIG. 2.

[0515] In FIG. 75, the contents of the tool are designation of displaycolor of lines, characters and regions, output method of designinformation, reference value (design data) required for each design, andnotation of respective parts data. In the twenty-sixth embodiment, theproduct shape data is displayed by “CYAN”, the undercut portion isdisplayed by “PINK”, the parting line is displayed by “YELLOW”, thecavity/core is displayed by “MAGENTA”, the mold base is displayed by“WHITE”, and the ejector pin is displayed by “BLUE”. The display 19 maydisplay lines, characters and regions based on such classification ofcolor.

[0516] In the twenty-sixth embodiment, the undercut portion may beoutput to the display 19 by “GRPHICS”, and the ejector pin and themanufacturing jigs of the mold parts may be output to the printer 20 by“PAPER”.

[0517] In addition, in the twenty-sixth embodiment, as for an approachallowable distance (hole interference check distance) between theejector pin hole and other holes, 3 mm may be registered as an isolationstandard value. As for an extrusion stroke a to the length of theejector pin, 0.1 mm may be registered as an isolation standard value. Asfor an extrusion stroke to the manufacturing jigs of the mold parts, 10mm may be registered as an isolation standard value. As for an offsetamount of the base of the manufacturing jigs, 10 mm may be registered asan isolation standard value.

[0518] With respect to ejector pin design, parts data concerning thecore block may be displayed by “CORE-BLOCK”, parts data concerning thecore plate may be displayed by “CORE-PLATE”, parts data concerning theupper ejector pin may be displayed by “EPR”, and parts data concerningthe lower ejector pin may be displayed by “EP”.

[0519] With respect to cooling water path design and nest design, partsdata concerning the cavity plate may be displayed by “CAVITY-PLATE”,parts data concerning the cavity block may be displayed by“CAVITY-BLOCK”, parts data concerning the core plate may be displayed by“CORE-PLATE”, and parts data concerning the core block may be displayedby “CORE-BLOCK”.

[0520] Next, in step W2, the designer may decide whether or not thedefault value must be varied. If the default value must be varied (YES),then in step W3 the default value is varied. The designer may vary thedefault value by rewriting the contents of the configuration file. Thus,designation of display color of lines, characters and regions, outputmethod of design information, reference value (design data) required foreach design, and notation of respective parts data can be varied freely.

[0521] Unless the default value must be varied in step W2 (NO), then instep W4 the system is started. In response to starting of the system,the display 19 may display the product shape by “CYAN” in compliancewith the configuration file.

[0522] In step W5, if the designer designates the information outputmethod “GRPHICS” to detect the undercut portion, the display 19 maydisplay the undercut portion in compliance with the configuration file.

[0523] In step W6, in order to form the parting, the display 19 maydisplay the color of the parting by “YELLOW” in compliance with theconfiguration file.

[0524] In step W7, in order to form the mold base and the cavity/core,the display 19 may display the color of the mold base by “WHITE” and thecolor of the cavity/core by “MAGENTA” in compliance with theconfiguration file.

[0525] In step W8, when checking interference between holes, the ejectorpin design section 66 may execute check process of interference betweenpin hole and other holes depending upon the standard value=3 mm readfrom the comfiguration file.

[0526] In step W9, when designing the ejector pin, the ejector pindesign section 66 may add the extrusion stroke α=0.1 mm being read fromthe configuration file to a maximum height of the ejector pin.

[0527] Further, in step W10, when designing the electric dischargemachining electrodes, the designer may design the electric dischargemachining electrodes (manufacturing jigs of the mold parts) based on theextrusion stroke=10 mm being read from the configuration file. Thedesigner may also design the base of the electrodes based on the offsetamount being read from the configuration file.

[0528] Like the above, according to usage of the configuration file ofthe mold design system of the twenty-sixth embodiment of the presentinvention, it should be noted that, although a plenty of automaticprocessing are being employed, display color of lines, characters andregions, output method of design information, reference value (designdata) required for each design, and notation of respective parts datacan be varied arbitrary in step W3. Therefore, the mold design systemwhich is fitted to each designer can be built up. Furthermore, the inputitems needed in designing process can be reduced by preparing theconfiguration file in advance.

[0529] (27) Twenty-Seventh Embodiment

[0530]FIG. 76 is a flowchart illustrating design process of the moldaccording to the twenty-seventh embodiment of the present invention.FIG. 77 is a view for use in supplementary explanations, i.e., aperspective view showing an injection mold device when individualattributes are allotted to names of respective parts of the device. Inthe twenty-seventh embodiment, in order to improve operability of themold design system, first names (attributes) are assigned to data groupsfor designing the mold, and then nest type mold or direct impressiontype mold may be designed based on these attributes.

[0531] In FIG. 76, in step X1, the designer may first assign a name(attribute) of “PART” to product shape data at starting the designsystem. If there are a plurality of data groups, the designer may selectand assign another name.

[0532] For instance, in step X2, when forming the parting line, thedesigner may assign a name of “PARTING-LINE” to a data group of theparting line.

[0533] In step X3, when correcting shrinkage rate, the designer mayselect a data group of “PART” and “PARTINGLINE”. In that case, theproduct shape correction editor 14 may read out a data group of “PART”and “PARTING-LINE” from the memory 11 and the memory 13 and, as hasexplained in the third embodiment, then automatically correct theproduct shape.

[0534] In step X4, when designing the cavity and the core, the designermay assign a name of “CAVITY/CORE-BLOCK” to a data group of cavity/core.In the case that the nest type mold is designed, there exists a datagroup concerning the cavity/core block.

[0535] In turn, in step X5, when designing the mold base, the designermay assign names of “TCP”, “CAVITY-PLATE”, “COREPLATE”, “SP”, “SB”,“EPR”, “EP” and “BCP” to groups of the mold base data. In FIG. 77, areference 31 denotes fixing side clamping plate which is displayed as“TCP” in the system; 32, fixing side mold plate being displayed as“CAVITY-PLATE”; 33, movable side mold plate being displayed as“CORE-PLATE”; 34, support plate being displayed as “SP”; 35, spacerblock being displayed as “SB”; 36, upper ejector plate being displayedas “EPR”; 37, lower ejector plate being displayed as “EP”; 38, movableside clamping plate being displayed as “BCP”; 39, fixing side blockbeing displayed as “CAVITY-BLOCK”; 40, movable side block beingdisplayed as “CORE-BLOCK”.

[0536] In the event that the direct impression type mold is designed,there exists data groups as to the cavity plate and the core plate. Themold base design section 61 may read out data groups of “TCP”,“CAVITY-PLATE”, “CORE-PLATE”, “SP”, “SB”, “EPR”, “EP” and “BCP” from thememory 12 and, as has discussed in the twelfth and twenty-fifthembodiments, then form the mold base.

[0537] In step X6, when forming the parting plane, the cavity designeditor 15 may form the parting plane on the basis of data group of thename “PARTING-LINE”. The designer may assign a name of “PARTING-SURFACE”to a data group of the formed parting plane.

[0538] Subsequently, in step X7, the designer may detect whether or notthere is the data group having the name of “CAVITY/CORE-BLOCK”. If“CAVITY/CORE-BLOCK” has been detected (YES), then the process advancesto step X8 since this corresponds to design of the nest type mold.

[0539] In step X8, the cavity design editor 15 may form a cavity portionof “PART” in “CAVITY/CORE-BLOCK”. Here the cavity design editor 15 mayread out the data groups concerning “CAVITY/CORE-BLOCK” and “PART” fromthe work memory 13 and, as has discussed in the ninth and twenty-thirdembodiments, then execute data processing.

[0540] In the next, in step X9, the cavity design editor 15 may splitthe mold block into two parts in “PARTING-SURFACE”. The cavity designeditor 15 may read out the data group of “CAVITY/CORE-BLOCK” from thework memory 13 and, as has described in the tenth embodiment, then splitthe mold block into the cavity and the core based on the parting plane.Two split portions are referred to as “CAVITY-BLOCK” and “CORE-BLOCK”.The “CAVITY-BLOCK” may serve as the fixing side block and the“CORE-BLOCK” may serve as the movable side block.

[0541] On the other hand, there has been no data group as to“CAVITY/CORE-BLOCK” in step X7 (NO), then the process advances to stepX10 since this corresponds to design of the direct impression type mold.In step X70, the designer may combine data groups of “CAVITY PLATE” and“CORE PLATE” with each other into a data group, and then assign a nameof “CAVITY/CORE-PLATE” to the data group. To combine two data groupsinto one group means the fact that two plates are stacked.

[0542] In turn, in step X11, the cavity design editor 15 may form acavity portion of “PART” in “CAVITY/CORE-PLATE”. Then in step X12, thecavity design editor 15 may split the mold block into two parts in“PARTING-SURFACE”. Two split portions are referred to as “CAVITY-PLATE”and “COREPLATE”. The “CAVITY-PLATE” may serve as the fixing side moldplate and the “CORE-PLATE” may serve as the movable side mold plate.

[0543] In addition, in step X13, when designing the cooling water path,the display 19 may read data groups relating to “CAVITY-BLOCK” or“CAVITY-PLATE” and “CORE-BLOCK” or “CORE-PLATE” from the work memory 13,and then display the fixing side block or the fixing side mold plate andthe movable side mold block or the core side mold plate on the screen ofthe display 19.

[0544] In step X14, when designing the ejector pin, the display 19 mayread data groups as for “CORE-BLOCK”, “CORE-PLATE”, “EPR” and “EP” fromthe work memory 13, and then display the core block, the core side moldplate, the support plate, and the ejector plate on the screen of thedisplay 19.

[0545] If the location of the ejector pin has been decided by thedesigner here, the ejector pin design section 66 may form pin holesthrough four related parts, i.e., core block, core side mold plate,support plate, and upper ejector plate. In order to form the pin holesso as to penetrate four related parts collectively, consistentcoordinate systems of data groups concerning “CORE-BLOCK”, “CORE-PLATE”,“EPR” and “EP” are needed. If the consistent coordinate systems havebeen achieved, profiles enabling the holes to be formed in these fourrelated parts simultane-ously may be designed on the same position asthat of the designated ejector pin.

[0546] In this manner, according to the twenty-seventh embodiment of thepresent invention, it would be evident that, since names (attributes)have been assigned to data groups of the product and the mold parts,only data groups required for in the course of respective design stagesmay be selected. Therefore, since data groups being obstructive to thedesign operation has been unloaded into the memory, design operation canbe simplified.

[0547] Moreover, according to the twenty-seventh embodiment of thepresent invention, it would be understood that, although four relatedparts into which the pin holes must be formed are needed, this operationmay be effected together in the ejector pin design section 66 byassigning the attributes for unifying the coordinate system of the datagroups concerning core bock, core side mold plate, support plate, andejector plate.

[0548] (28) Twenty-Eighth Embodiment

[0549]FIG. 78 is a flowchart illustrating design process of holeportions in the mold parts according to the twenty-eighth embodiment ofthe present invention. FIGS. 79A to 79C are views for use insupplementary explanations, i.e., perspective views showing interferencebetween the cooling water path and the ejector pin holes. In thetwenty-eighth embodiment, there is disclosed a method for designing theejector pin holes and holes for the cooling water paths, etc. not tooverlap with each other. In FIG. 78, in step Y1, the designer may firststore information as to all holes of the mold parts in the designsystem. Tapped holes and guide holes for fixing the mold parts, coolingwater paths for adjusting the temperature of the mold, ejector pin holesfor ejecting the product from the mold, etc. are intended for theinjection mold. These data may be stored in the design data memory 11.

[0550] In step Y2, the designer may select design items relating to holeformation of the mold. As has been explained in the twentiethembodiment, the design items are, for example, correction of moldingshrinkage rate, formation of cavity/core block, determination of moldbase, formation of the parting plane, design of gate, runner and sprue,design of mold temperature adjusting water path, design of ejector pin,check of hole interference, split of nest structure, and design of slidecore. For example, as shown in FIG. 79A, the designer may select designof the mold temperature adjusting water path to design the cooling waterpath 44 in the fixing side mold plate 32.

[0551] Next, in step Y3, the designer may design a certain hole profilein the selected design items. Then, as has explained in the seventeenthembodiment, the designer may design the cooling water path.

[0552] In step Y4, the ejector pin design section 66 may detect whetheror not a hole to be designed (referred to as “design hole” hereinafter)interferes with other holes. For instance, the design hole is thecooling water path 44 whereas, as shown in FIG. 79B, an objective ofother holes is an ejector pin hole 45 which penetrate movable side block40, fixing side mold plate 32, and upper ejector plate 33 together. Asshown in FIG. 79C, based on that the distance between the location ofthe cooling water path 44 and the location of the ejector pin hole 45can be kept more than a standard value, it may be determined whether ornot the cooling water path 44 does interfere with the ejector pin hole45. An isolation standard value=3 mm, which having been discussed in thetwenty-sixth embodiment, may be used as the foregoing standard value.This standard value may be stored in the configuration file.

[0553] Unless the interference between the cooling water path 44 and theejector pin hole 45 has been caused in step Y4 (NO), then in step Y5hole profile data of the cooling water path 44 are stored. On thecontrary, if the interference between the cooling water path 44 and theejector pin hole 45 has been caused in step Y4 (YES), then in step Y6interference portion of the hole may be depicted on the display 19, asshown in FIG. 79C. Then this hole profile data may be removed.

[0554] In step Y7, the designer may determined whether or not designoperation of entire holes have been completed. If the entire holes havebeen designed (YES), then the process goes to step Y8. Unless the entireholes have been designed (NO), then the process returns to step Y3 wherethe design operation of the hole profile may be continued. If all holeshave been designed, then in step Y8 the designer may determine whetheror not the design items must be changed. If the design items have beenchanged (YES), then the process proceeds to step Y2 where the designitem may be selected. While, unless the design items have been changed(NO), then the hole design operation is terminated.

[0555] In this fashion, according to the hole design method of the moldof the twenty-eighth embodiment, it should be noted that, sinceinterference between holes in design and other holes has been checked instep Y4, design errors such as overlapping of the cooling water path 44and the ejector pin hole 45, for example, can be prevented.

[0556] (29) Twenty-Ninth Embodiment

[0557]FIG. 80 is a flowchart illustrating design process of themanufacturing jigs of the mold parts according to the twenty-ninthembodiment of the present invention. FIGS. 81A to 81F are views for usein supplementary explanations. In the twenty-ninth embodiment, the casemay be particularly shown wherein electrodes (manufacturing jigs) fordischarge-working the corners inside of the cavity block in an R-likeshape should be designed. In FIG. 80, in step Z1, the designer may firstselect concerned mold parts. For instance, in case the corner portionsof the product shape 46 would be finished to have an R shape, as shownin FIG. 81A, the inner corners of the cavity block must be worked inadvance in an R-like shape. To this effect, the designer may select thecavity block 39, as shown in FIG. 81B. The display 19 may display thecavity block 39 designated by the designer. The profile data of othermold parts have been unloaded into the memory.

[0558] In step Z2, the designer may designate a range of themanufacturing jigs to the mold parts being displayed on the display 19.The range may be designated via the keyboard 17. In FIG. 81B, the rangeof the manufacturing jigs are the region for connecting both ends of theconcave portion of the cavity block 39. The width of the manufacturingjigs may freely decided by the designer.

[0559] Subsequently, in step Z3, the designer may form an extrusionprofile 47A having the range as the sectional shape. In FIG. 81, theextrusion profile 47A may comprise a portion extending from the backside of this sectional shape to the bottom of the cavity block 39 and aportion extruded from the front side of the sectional shape by apredetermined distance. Since this predetermined distance has beenstored in the configuration file as an extrusion amount, it can be usedby reading from the file. In the twenty-ninth embodiment, thepredetermined distance=10 mm is set as a standard value.

[0560] Thereafter, in step Z4, the concave shape of the cavity block(mold profile) 39 may be transferred to the extrusion profile 47A. Inother words, the sectional shape of the extrusion profile 47A isprojected onto the concave portion of the cavity block 39 to transfer Rshape, side shape, and bottom shape of the corners. Transfer process mayexecute by subtracting unnecessary profile portions from the solidprofile formed by projection of the sectional shape in terms of Booleanoperation. Thereby, as shown in FIG. 81D, an electric dischargemachining electrodes 47 may be designed.

[0561] In step Z5, a reference location from the center of the injectionmold is designated on the electrode 47. In the twenty-ninth embodiment,for instance, the reference location may be designated like (−200, 350).The designation of the reference location has to be designated toexecute electric discharge machining the concave portion of the cavityplate exactly.

[0562] Next, in step Z6, a base 48 may be formed on the electrode 47.The base 48 may be formed by adding an offset amount, as shown in FIG.81E, to dimension of the bottom surface of the electrode 47. The offsetamount may be read from the configuration file. In the twenty-ninthembodiment, a reference value is 10 mm. A thickness of the base may bedetermined arbitrarily by the designer. Consequently, the electrodes(manufacturing jigs) 47 for electric-discharge machining the innercorners of the cavity block 39 to have an R-like shape have beendesigned. Profile data of the electrode 47 may be converted intonumerical control data.

[0563] After this, in step Z7, the designer may determine whether or notinformation of the electrode 47 are output. If information of theelectrode 47 have been output (YES), then in step Z8 the display 19 mayoutput the profile of the electrode 47 on the screen according toinstruction of the designer. The printer 20 may also output informationof the concerned parts on the paper according to instruction of thedesigner. Output information corresponds to the mold parts being workedby the electrode 47. In the example shown in FIG. 81F, the case has beenillustrated wherein the concerned parts name is “CAVITY-PLATE”, thereference location of the electrode 47 from the center of the mold is(−200, 350), the profile of worked material is X=80, Y=90, and Z=40.Output information of the concerned parts may be offered to the moldmanufacturer.

[0564] On the contrary, unless information of the manufacturing jigshave output in step Z7 (NO), then in step Z9 the designer may determinewhether or not other manufacturing jigs should be designed. If othermanufacturing jigs have been designed (YES), then the process returns tostep Z1 where the mold parts may be selected. Subsequently, steps Z2 toZ8 may be repeated.

[0565] As has been stated earlier, according to the design method forthe manufacturing jigs of the mold parts of the twenty-ninth embodimentof the present invention, it would be evident that, since the designermay designate the range of the manufacturing jigs for the cavity block39 in step Z2 and the system may form the extrusion profile 47A havingthe range as the sectional shape in step Z3, the designer may design theelectric discharge machining electrode 47 in a manner interacting withthe system.

[0566] In addition, according to the twenty-ninth embodiment, it wouldbe apparent that, since the reference location from the center of theinjection mold may be designated on the electrode 47 in step Z5,electric discharge machining operation of the concave portion of thecavity plate can be performed exactly by placing the electrode 47 on thereference location.

What is claimed:
 1. An injection retold design method for correcting a profile of a product to be fabricated into a releasable profile from a mold comprising: (a) calculating a normal vector on a plane of a product shape and a reference vector in a mold opening direction; (b) detecting a normal vector having the opposite direction to that of the reference vector so as to detect undercut portion; acid (c) after the step (b), farming a split borderline for a slide structure of the mold.
 2. An injection mold design method as claimed in claim 1, further comprising: (d) after the step (c), editing a main split borderline that splits a mold block into a cavity a core.
 3. An injection mold design method ac claimed in claim 7, further comprising: (e) after the step (d), executing a loop check for the main split borderline to check whether the main split borderline is closed or not; and (f) if the main split borderline is checked as being not closed in the step (e), repeating the steps (c) to (e) until the main split borderline closes.
 4. An injection mold design method as claimed in claim 2, wherein the step (d) further comprising: (g) removing temporarily part of lines or planes constituting a product shape or a mold profile from a screen; and (h) replotting the lines of planes on the screen after the editing operation of the main split borderline is completed.
 5. An injection mold design method for correcting a profile of a product to be fabricated into a releasable profile from a mold comprising: (a) designating a plane element of the product; (b) calculating a shrinkage vector of a resin whose surface defines the plane element where the vector is defined when the resin shrinks; (c) multiplying a norm of the shrinkage vector and an area of the plane element together to obtain a shrinkage force; (d) calculating a sticking strength of the product to the mold by multiplying the shrinkage force and a certain coefficient; and (e) judging whether an ejector force of an ejector pin is greater than the sticking strength of the product.
 6. An injection mold design method as claimed in claim 5 further comprising the step of: (f) correcting the product shape if the ejector force of the ejector pin is judged as being not greater than the sticking strength of the product in the step (e); and (g) repeating the steps (a) to (f) until the ejector force of the ejector pin becomes greater than the sticking strength of the product.
 7. An injection mold design method as claimed in claim 6, wherein the step (f) further comprising: (h) removing temporarily part of lines or planes constituting the product share or a mold profile from a screen; and (1) replotting the lines or planes on the screen after the correction operation is completed.
 8. An injection mold design method according to claim 5 further comprising the step of: (j) calculating a total shrinkage force of a core surface of the product based on the sticking strength of the product; (k) calculating a total shrinkage force of a cavity surface of the product based on the sticking strength of the product; (l) judging whether the total shrinkage force of the core surface is greater than the total shrinkage force of the cavity surface; (m) correcting a product shape if the total shrinkage force of the core surface is judged as being not greater than the total shrinkage force of the cavity surface in the step; and (n) repeating the steps (a) to (e) and (j) to (m) until the total shrinkage force of the core surface becomes greater than that of the cavity surface.
 9. An injection mold design method as claimed in claim 5 further comprising the step of: (o) calculating a normal vector on a plane of a product shape and a reference vector in a mold opening direction; (p) detecting a normal vector having opposite direction to that of the reference vector so as to detect undercut portion.
 10. An injection mold design method for correcting a profile of a product to be fabricated into a releasable profile from a mold comprising: (a) calculating a degree of deformation of a product based on a shrinkage rate of a resin that constitutes the product.
 11. An injection mold design method as claimed in claim 10 further comprising the step of: (b) judging whether the product is releasable from the mold based on the calculated degree of deformation; (c) correcting a product shape if the product is judged as being not releasable from the mold in the step (b); and (d) repeating the steps (a) to (c) until the product becomes releasable from the mold.
 12. An injection mold design method as claimed in claim 11, wherein the step (c) further comprising: (e) removing temporarily part of lines or planes constituting a product shape or a mold profile from a screen; and (f) replotting the lines of planes on the screen after the correction operation is completed.
 13. An injection mold design method for correcting a profile of a product to be fabricated into a releasable profile from a mold comprising: (a) forming a mold block; (b) reading a product shape data; (c) displaying the mold block and the product so as to overlap each other on a screen; and (d) judging whether a size and a profile of the mold block is suitable to the product shape.
 14. An injection mold design method as claimed in claim 13, further comprising: (e) modifying a dimension of the mold block if the size and the profile of the mold block is judged as being not suitable to the product shape in the step (d).
 15. An injection mold design method as claimed in claim 13, further comprising; (f) after the step (d), making a portion in the mold block hollow where the portion corresponds to the product shape.
 16. An injection mold design method for correcting a profile of a product to be fabricated into a releasable profile from a mold comprising: (a) forming a split plane by extending a designated split borderline in parallel to a designated direction when a mold block is split into a core and cavity; and (b) forming a split borderline for a slide structure of the mold block after the step (a).
 17. All injection mold design method as claimed in claim 16, further comprising: (c) forming a slide split plane based on the split borderline for the slide structure.
 18. An injection mold design method as claimed in claim 17, further comprising: (d) dividing the mold block into the core and the cavity based on the slide split plane.
 19. An injection mold design method as claimed in claim 18, further comprising: (c) judging whether the mold block can be opened or not by checking whether there exists interference between the core and the cavity or not.
 20. An injection mold design method as claimed in claim 19, further comprising: (f) repeating the steps (a) to (e) until the interference between the core and the cavity disappears if the mold block is judged as being not opened. 